Organic groups users cant leave groups I cant find a link where I can add for people in a group to be able to leave the group.

back in the older version it was something like og/member/group_id, but that doesnt work anymore.

I'm using drupal 7 with OG version = "7.x-2.0-alpha2"
It's /og/%/%/unsubscribe. See og_ui_unsubscribe() in og_ui.pages.inc to learn what are the arguments passed onto this.