To leave a team
Start in the You tab.
Scroll down to the team you wish to leave
Press the 3 dots to the right of the team and select leave team
If you are an admin, you will be prompted to pass over the admin rights to someone else before you leave. This is so that the team is not left without an admin. To find out how to pass over your admin role, click here.
Click here if you would like instructions on how to delete a team instead.