If you removed stuff off the tablet and it is saying that, either the app is bad or you have something on the device that you don't want.
First I would try checking the tablet for viruses and malware. Should that not fix it, you may want to uninstall your Facebook app, then reboot the tablet and then download and install it again. Make sure you save anything you want first, so you don't lose it.
Should that not work either, you may well have to "Hard Reset" the device.
NOTE: Doing this will clear 'all' the data on your tablet, so it is suggested you not choose this option unless you have to, or aren't worried about losing anything on the device.
Be sure you back up any data you want to keep, to a computer or cloud account, before...