If you are the Team Owner, you will have access to delete a team.
From the app dashboard:
1. Press the downward arrow in the top left corner of the screen
2. Press the 'Manage Teams Icon' (icon has a screwdriver and a wrench on it)
3. Find the team you are looking to leave and press the delete icon (right hand side)
4. Press 'Delete Team'
From the Web:
1. Click the list of Teams in the top right
2. Select 'Manage Teams' at the bottom of the list
3. Press 'Delete Team' or Transfer Ownership of the team to another team member and then Leave the team.