I have a user (or any user in fact), who has a Standard salesforce profile, IE not a System Admin profile, who's able to edit and even reject opportunities that he submitted. He should not be able to edit them because the Record Editability property on the approval process = "Administrator ONLY". Secondly, he's even able to Reject his own submission, which makes no sense to me either. Can anyone help? Thank you!
Admins or any user with "Modify All" access to the object can edit a locked record. I would verify there are no permission sets or profiles associated to the user that provides this access.