how to destroy a session in the proper way.

and yes use active record session then your tmp/session folder will be
empty.

The folder will be empty but you'll have a growing sessions table.
Either way you need a cronjob (or pick your favourite mechanism for
scheduling scripts to run) that deletes sessions a some regular
interval.

Fred

… or you can just call a cleanup method at the login page depending on the amount of traffic your site gets, works just as well.

Best regards

Peter De Berdt