Also, you may delete (and optionally purge) your account under the gear icon from the dashboard.

Hello,

We’re sorry to see you go. You can find instructions for deactivating your account at the bottom of this page:
https://www.digitalocean.com/docs/accounts/profile/

If you have a team account, you can find those instructions here:
https://www.digitalocean.com/docs/accounts/teams/deactivate/

Regards,
Alex