To leave any mod teams that you are a member of, you can do so by logging in to the mod.io website and clicking the "My Teams" icon on the left side of the page.
Make sure that you are on the Mods view.
On this page you will find a list of all your mod teams. To leave a team, simply select the "leave team" button next to the team that you wish to leave.
Please note: if you are the sole member of the team you will be unable to leave that team unless you add another team member and promote them to leader.