Hello, 

My "joined jam" start to be a bit noisy, is it possible to leave a jam ? Specially if not submitted anything .

For an active jam, go to the jam’s page and select the “Leave jam” link near the top.

For a past jam you did submit to, follow the link on your project page to the jam page created for that project. Select the “Remove this submission” link that’s near the top left.

For a past jam with no submission… I don’t know of any way to clean up our jams list.

Apparently leave jam button use the jam "id" https://itch.io/jam/404592/unjoin
Maybe it's simple to "find this id" for a past jam ?