You will not be able to delete your account if the balance is negative. See here for more information on the negative balance.
To delete an account, go to Settings.
And click Delete account opposite the Login field.
Then select a reason for deleting the account, enter the password you use to sign in and click Confirm. After that the account will be deleted, the following data will be erased:
- contact details, including phone number and email;
- ad spaces — they will be marked as deleted;
- full name;
- payment details;
- guest accounts — if any.