If I disassociate a post from my account,
- will I lose the rep I have gained from it?
- will I gain back the rep I lost from it?
- if I keep the rep, will it still show on my profile?
If you disassociate a post from your account, it is like your never asked the question. All rep (positive or negative) associated with the question (or answer) is removed from your account. So yes, you will lose any rep you gained from the question and you will regain any rep you lost from the question. Nothing about the question will show up on your profile.