can you uninstall yosemite

You can revert to a previous Mac OS X, but to do so you should have a backup of your contents, and if you have a TimeMachine or other backup of the previous Mac OS X the job is easier. To go back you will have to erase the hard drive and then reinstall the prior Mac OS X version.

What backups do you have, what Mac OS X came on your MBP, was it Mavericks?

Install or Reinstall Yosemite, Mavericks, Mountain Lion, or Lion from Scratch

Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.

How to Clean Install OS X Yosemite

OS X Mavericks- Erase and reinstall OS X

OS X Mountain Lion- Erase and reinstall OS X

OS X Lion- Erase and reinstall Mac OS X

Note: You will need an active Internet connection. I suggest using Ethernet if possible

because it is three times faster than wireless.