You can see all of your groups by clicking "my groups" on the teal colored main navigation. Open the group you wish to leave.
Click the "Active Member" button on the group About page.
When you click the "Active Member" button you should see a pop up that reads: "Are you sure you wish to leave the group?" with the option to click "Yes" or "No". Clicking "Yes" will remove you from the group. Note that you cannot leave a group for which you are an Admin or an Owner. In order to do so, you must ask another group admin to demote you to a normal member first.
At any point you can view all of the groups you belong to by clicking My Groups in the main Trellis menu.
You can search or sort these groups to help you find them more easily.
Further Questions? Contact the Trellis team at firstname.lastname@example.org