Should I make a backup of OSX before bootcamping Windows 10

I have the Mid 2012 Macbook Pro. I want to know if I should make a backup of osx, before dualbooting windows 10. I already have all my files backed up to the cloud, but not osx. Do I need to do so? Also, how is the performance of windows 10 on a mac? Am I able to un-dualboot windows 10 from my mac, if i dont like it?

Usually you would want to make a backup of OS X (macOS) before dual-booting Windows 10 just in case something messed up the hard drive you can go back to it. Regular Time Machine backup is good enough. Unless you want to take some risk, you can do it without a backup. I didn't do any backup before installing Windows 10 and it worked just fine, I don't need to restore or anything.

How Windows 10 performs depends on how good your CPU is and how much RAM you have. Usually when I am using just some apps, like Edge, MS Word, etc., they only consumes around 2GB of memory. Windows 10 is pretty well optimized so the performance shouldn't be very bad on MacBooks. If you want to remove Windows 10, you can go back into Bootcamp Assistant on your Mac. If Windows 10 is installed Bootcamp Assistant will have an option to remove Windows 10 for you.

More information on removing Bootcamp can be found here.

I would strongly recommend making a backup before setting up Boot Camp. Setting up Boot Camp involves repartitioning the disk into an OS X partition and a partition for Windows, but OS X doesn't know how to format the Windows partition into NTFS. So, it formats the Windows-to-be partition in the FAT32 format, and expects you to use the Windows installer for reformat it into NTFS. If you don't do this quite right, the Windows installer may reformat the OS X partition as well, causing complete data loss.

Thus, it's much safer if you have a full backup. Just in case.