[Edit: Lol, Poney probably gave a better answer.]
Ahh, it's ~essential you factory reset when moving from stable to beta.. ahh. I ~can't suggest much other than:
At least take a nandroid backup before you start deleting and save it extrenally. If you want copy the internal storage as well. You'll probably lose apps and app data. ~Most of them might use accounts amd are backed up online. The offline apps though...
when i try to do a nandroid backup i receive the message: Failed.
i will try to flash stable back.