You can freeze user accounts to prevent them from working in your business while you undertake the steps to DEACTIVATE them. So, until you figure out how to remove this user from the Role hierarchy, you can update the owner of the entries he created/from any location where this user is employed. For this, we can USE the FREEZE BUTTON on the user record.  If we CLICK the FREEZE button, the user will no longer be able to LOG in to the application. Changing user accounts in the state does not free up existing user licences for use in your organisation. To release the licence, we must deactivate the user.