Do my parents have a right to control me as an adult?

I am a adult in my 30's and my parents are still very controlling even when I am on my own and don't live with them. They treat me like a child and tell me not to post on Facebook or use my account because it's personal. I know I have a disability but they do not have power of attorney or do not look after me. They tell me they will find a way to take my account away and that I will be in a lot of trouble or that they will make sure I get the proper help I need if I go about their wishes. Is this normal behavior of them and do they have any right to do this? Even when I refuse and say I don't have to listen to them and that I am an adult with doing what I want as long as it is legal and doesn't violate the terms, they still say they need to get involved and that I need to listen to them or there are going to be consequences. One will be taking my account away and two will be them never supporting me again.

What should I do in a situation like this?