How can I uninstall OS X Yosemite and return to OS X Mavericks?

so did you "restore" from back up or just reinstall? im restoring but its taking a long time. i hit cmd r chose time machine back up chose the date and after a few hours with a meter it brought me to the start up screeen.this is where ive been for hours now from 3 am to 10 pm, did it take you this long? im on a late 2012 iMac connected to a 3 tb external hd/ i had a 1 tb hd with only 300 gb of stuff on it. i think the chord is usb 2.0

Wow I really don't know.
Yeah that is exactly what I did. Restart, CMD+R...which did take about 3, 4 minutes of that Yosemite loading bar...which didn't move, before I finally saw the gray screen and options, that part made me nervous.

I chose Restore from Time Machine Backup, gave me the list of dates, I chose the latest one (Oct 15, 11:20something PM)

Gave me an initial time of 1 hour 57 minutes, iquickly the time dropped to 90 minutes. In reality I think the whole process took about 1 hour. It rebooted, it prompted me to sign in with my AppleID again - iCloud, Messages, etc.

God, 3am Tuesday morning until 10pm Tuesday night..still going? That doesn't sound right at all.
I have a 1TB Mac HDD - noticed the space remaining jumped a little to 810GB
My Time Machine backups are on a Western Digital 2TB External HD.

The iMac is a Mid 2011 27" with upgraded 12GB RAM.

im working with a late 2012 imac witha western digital 3 tb hd. i restored my drive from a particualar date , the meter said 4 hrs about 3 hrs into it it sped up and restarted the machine . all i see is a circle spinning under the apple sign. i started at 11 pm and now its 7 am i have a 1 tb had but only usd abt 300 gb of space. should i letit keep running?

Restoring from a backup will do exactly that: it will restore everything to the way you had it.

Something is not right, I never once had the spinning wheel during the restore, normal pointer cursor was always there. Shouldn't take 24 hours also, to me, obviously it sounds like it's stuck. I don't know if the computer had some kind of 'hiccup' during the restore process or that restore file is somehow corrupted causing the freeze.

I don't want to tell you what to do, I'm not an expert with hardware. I'm guessing the only thing you can try at this point is to hold the power button down until it turns off. - Pull out the plug from the back of the MAC for 15-20 seconds, plug it back in. Turn the power back on, hit CMD-R and try the process again? If you have a different restore file, try that one.

You can look at these other Apple forum troubleshooting post for any advice.
OS X Mavericks crashing on installation

Why won't Mavericks install?

CNET "How to manage a failed OS X Mavericks installation"
- http://www.cnet.com/how-to/how-to-manage-a-failed-os-x-mavericks-installation/

I just updated my software yesterday (OS X Yosemite) and my computer is operating incredibly slow. Whatever I do I'm constantly getting the spinning wheel. Seriously Apple you need to sort out your software issues, it seems that you have gone backwards instead of forwards recently when launching new products. It is impossible to work like this and considering the rates you charge for your products I expect better as a loyal customer. Are you offering a solution for these problems? Are you going to fix these software issues any time soon?

You really need to start troubleshooting your Mac because it appears to have problems that Apple is not going to be able to fix for you.

Oh, so use a different external hard drive to back everything from time machine in there, then once i erase everything in my current hard drive using Internet Recovery, I'd go back to the external hard drive and move all of my files back to my internal hard drive?

Maybe this was already solved, did you check the App store for any updates to these programs? I would seriously HOPE you have a free compatibility update for Yosemite, those are pricy programs!

Apps like Pages, iMovie, Keynote, etc were updated in 10.10. Since I went back to Mavericks..these newer versions will not work anymore. I understand that and thats fine.

I too wish to uninstall Yosemite for a number of reasons I've been discovering daily since first downloading it a few days ago. I have a iPhone 4S that only came with 6GB, have a handful of apps that take up 5GB. So there not nearly enough room for this newer operating system (even if there were it would be painfully slow). The 4th G iPod Touch has the same issues. The older iCloud & the newer are not compatible. The older straight forward Clear History is now Clear History & Website Data, which will delete all your saved password settings (who designed that). And on & on, really see absolutely no advantage in Yosemite over the Mavericks-most notably the incompatibility issues in so many areas, should've been a disclaimer.

Almost - get an external drive. Use TM to backup everything. Then use Internet Recovery (Command + Option + R) to boot from, and then you have a choice: you can erase your hard drive or you can restore from the attached TM backup. I don't use TM at all, so cannot give detailed instructions on it; but I do know that you will need to erase the drive if you want to "downgrade" your OS.

Another option: instead of backing up the entire system, simply back up your important files (drag 'n drop) to the external drive, unplug that drive, go into Internet Recovery, erase the internal drive, and choose to reinstall the OS - with that method, you should be getting the OS originally installed (if that was Lion or later). Once that is done, you can drag your files back.

FWIW, do you have a backup with TM that still has Mavericks on it? If not, doing a backup now will just put Yosemite on the backup.

Ahhh, okay. All of that makes so much sense now. And no, I've never used TM. Can I select what I want to back up onto TM, do you know?

I might have to get a 1TB hard drive and do all of this anyway, cos the HD makes grinding noises whenever I lift/move my macbook pro. I think it's messed up..

Also, what external hard drive would you recommend?

There are some things I like about Yosemite, the more I use it, it's new screensaver options, improved notifications, how bookmarks are saved in safari, including some others. The business 2D look of the app icons, although it bothered me at first, I'm getting used to. Still the extremely slow speed is not one of them. Like several other posters in this forum, I also will get the spinning beachball. It has occurred several times today, already. I had planned on purchasing 2 two GB RAM modules for an early/mid 2009 iMac, because Mavericks ran slower then Snow Leopard. Still Yosemite moves like an absolute Snail, making Mavericks look like the Hare. Will increasing my Ram, make my iMac work properly again, or will it only help a little. Currently I have two 1 GB RAM installed. Also how long will it work? My iMac is only 5 years old, and I realize that in the computer world, that is ancient history. Still I do not have the income to purchase a brand new iMac for more then a grand, every 5 years, or less. If macs continue to become, more & more RAM hungry, I am probably going to be forced into purchasing a PC again. I hate to admit that, but because Mac's, are becoming so bloated, they maybe forcing me too.

I have some older LaCie's and my new favorite is/are (I have three of them - 2 regular size, one mini):

http://eshop.macsales.com/shop/firewire/

(Mercury Elite Pro/mini)