Service: StumbleUpon is a “discovery engine” that helps surface and recommend web content to its users.
How To Delete An Account:
1. Log in to StumbleUpon.
2. Once you're logged in you can delete you account from this page.
3. Enter password to confirm your intentions.
The account will officially be deleted 14 days after the request, during which time the account can be reactivated.
Related Article: How To Close Online Accounts