On the Browser:
Log in to the website.
At the top right corner of the screen, click the user icon or profile picture.
Click My Teams.
To the right of the desired team, click the three dots icon > Leave team.
Click Leave team.
On the App:
Open the app.
Tap Settings.
Locate the team to leave.
Tap the team and swipe to the left.
Tap Leave.
Tap Leave to confirm.