How to destroy a specific PHP session

Question

I am looking for insights into how to destroy a specific session in PHP. Through a partner website a user logs into the main website using a token and obtains a full session

Answer 1

The database solution means that the session database needs to be shared between mainwebsite and the partner site, which frequently isn't the case etc. Maybe something along these trivial lines would suffice?

mainwebsite/logout.php: