Can a Credit Union or Bank close a persons account without him or her knowing? ?

I recently returned to my home state after an extended leave of absence. I wanted to see if my old Federal Credit Union still had my account open. It turns they closed my account due under par fees. Can a bank legally do this?
Can a Credit Union or Bank close a persons account without him or her knowing? ?
yes if your account goes into a dormant state, federal law requires banks to charge a 5 dollar fee and sometimes that can lead to accounts to go negative and be sent to collections and then they close the account. Or if the account is just negative they can just close it.