As an Admin you can leave the label ONLY if the label has another admin. At any point of time the label must have atleast one (or more) Admin to it. Incase you are the only Admin and you wish to leave the label, but still enable the existing collaborators to continue using the label, you must appoint another collaborator as the Admin. Once you do this, you get an option on the console to 'Leave Label'
1. If you are the only Admin, you can only 'Delete Label' from Tandem as shown in the screens below
2. You must appoint another Admin ( refresh the screen), and then you get an option to 'Leave Label'