Objects are typically locked because another session edited them and hasn't published changes.
Review the sessions listed here:
If you find a session with locks/changes, right click on it and you should be able to publish or discard the session, which will release the lock.
(Note this is from R81.20, but similar options should show in R80.20)
Otherwise, you're going to have to edit the database manually to release the lock.
TAC should be able to assist with this, even though R80.20 is End of Support.