Yola accounts are completely free of charge and there are no strings attached! Your account is entirely under your control and you can delete it any time you wish. However, if in doubt, we recommend keeping your account, as deleting it will permanently remove all your sites from our system, but if you delete your account and would like to come back later, we will be happy to have you!
For security reasons, we require you to delete your own account, as this ensures that only the owner of the account can delete it. For more information on how to delete the account, check out this tutorial: Deleting your account.
You may also find this useful:
How can I delete a file in File Manager?