To delete a team you are in charge, check this article.
To leave a team you are no longer in, check this one.
To delete your SportEasy account:
- Go to the page "My SportEasy account" and click on "Edit profile"
- Go to the bottom of your profile page and click on "Delete my account"
Warning: deleting a SportEasy account is irreversible. You will no longer be able to access your account, teams, statistics history, etc.
Of course, you will always be able to create or join a team later by creating a new SportEasy account.