Can't resize partition - Size Greyed Out

Make sure you have a back up of everything!!!!!!

Ok, now you will need to boot to an external Recovery HD. So, since your Mac came preinstalled with OS X Mavericks, restart while pressing Command+Option+R. This will take you into Apple's Recovery HD.

Open Terminal from the OS X Utilities menu -- Utilities menu item then Terminal.

Do a diskutil cs list to find your Logical Volume UUID. Below is from your last post using that command and I have bolded the UUID you are looking for.

Adams-iMac:~ Adam$ diskutil cs list

CoreStorage logical volume groups (1 found)

|

+-- Logical Volume Group 60E0F187-9AAD-40DA-BC7F-663DDACE2213

=========================================================

Name: Macintosh HD

Status: Online

Size: 477478170624 B (477.5 GB)

Free Space: 0 B (0 B)

Next, type diskutil cs delete <UUID> to delete the Logical Volume Group and its Logical Partition.

For example, distutil cs delete 60E0F187-9AAD-40DA-BC7F-663DDACE2213 <----- This should delete the LVG, erase and reformat the partition to Mac OS X Extended.

After you do the above successfully, we'll take the next steps to finish up.

Great!

That's correct. Boot to the Recovery HD on Macintosh HD 2 or use Command+Option+R again and use Disk Utility to Restore to Macintosh HD. Then boot into Macintosh HD, open Disk Utility, delete Macintosh HD 2 and resize Macintosh HD.

Note: If the Restore above errors with the Destination being smaller in size than the Source, just resize the Source smaller than the Destination. For example, assume Macintosh HD 2 is 2TB and Macintosh HD is 1TB and you get the error. Resize Macintosh HD 2 to 1TB and try again. Disk Utility Restore is picky about the Destination being equal to or greater in size than the Source.

You need to click on the drive name at the very top (3 TB Apple HDD); then the Partition tab. From the Partition tab select the bottom Macintosh HD and then the '-' should appear for you to delete it. Click Apply. Then you can drag the right bottom corner to resize the TOP Macintosh HD.

The above assumes you really are booted to the top Macintosh HD. You might want to rename them both so you can tell the difference, restart into the top one; THEN do the above paragraph, just to be sure. Disk Utility Restore always creates the Destination with the same label as the Source.

Hrmm.. I don't have anything over 1TB. So, I'm not sure if there's a size issue.

Before we do any Terminal commands to fix this, try resizing the bottom one to 1.xGB so that there is free space at the end and a 1.x volume. If that works, then try to delete the newly resized volume. Resize - Apply... then Delete - Apply... hopefully you'll have free space and 1 Macintosh HD afterwards.

You also need to BE SURE you are booted into the top Macintosh HD. I suggested that you rename each so it wasn't confusing. My guess is that you are booted into the bottom Macintosh HD.

Not sure. Open Terminal and type diskutil list and post the results here.

I have zero experience with Bootcamp (Windows) so you're on your own for that one. So, I don't know if you have to go back into Bootcamp and do something or what and I can't advise you there.

I would try a PRAM reset first (Shutdown - power up while pressing Command-Option-P-R until you hear the boot chime a 2nd time) before reinstalling OS X Mavericks from the Recovery HD. Check your Startup Manager after the PRAM reset. If you still see your issue, then try the reinstall. If you DO reinstall, it won't harm your apps or data. But it's always wise to do a back up before you do.

That all looks good.

Try the PRAM reset. Otherwise, I'm out of options. Sorry.