I have ulcertive colitis uc diag. In 2001. Cscopy showed flareup and proctitis in 2010. Cscopy 2013 showed no uc but proct. Can uc disappear?

No. The disease will not disappear, but the symptoms and inflammation can subside and be controlled. It sounds like your symptoms are well controlled, this is a good thing. After 10 years with uc, make sure you continue with colonoscopy every 1-2 years.
It can. You dont say whether you are or have been on maintenance meds. However left sided colitis or proctitis seems to have a less aggressive course than that involving the whole colon. You still should be followed regularly by a gastroenterologist even if symptom free.