Only an Administrator can delete a company account. You'll also need to be logged into Playground first.
Go to Sign In page and ensure you're logged in.
Click on your username in the top right corner of the screen.
Click the Account button.
Scroll down the page. Click Delete account button.
After removing your company from Playground, all data, settings and assets stored in Playground will be permanently deleted and will be unrecoverable. If you wish to simply freeze your Playground account by cancelling all subscriptions, please read this article.
If you're one of multiple admins, then you can just delete your own account and that won't affect other users or the Company itself. To remove a company from Playground entirely, all admins should delete their own accounts, or remove all other admins and then delete your own account.