In order to leave a team, you must transfer ownership of the team first. To transfer ownership of a team:
From the web, log in to your teamlinkt account (app.teamlinkt.com)
Go to the Dashboard, click the Add/Join button beside the teams dropdown and select 'Manage Teams'
If you are the team owner, in the Actions column you will see a 'Transfer Ownership' button - click this
Select the Member you would like to transfer ownership to