Sorry, but the “worm” is the Apple ID or your Apple password, to be more specific.
If there are still apps on the computer that are connected to your ID, he will not be able to update them with his ID. You can change your ID Password, but you can’t, AFAIK, change your ID. If/when he tries to update anything that you ‘purchased’, he will be asked for your Apple info. The only ‘clue’ will be that your Apple ID (email address) will be in the dialog awaiting your password. At which point, the ‘worm’ re-appears.