Do this.
- Remove the domain from the control panel while the site is un-suspended.
- Enter your FTP software and login to your account (Online file manager or FileZilla, either will work).
- Open your plugins folder, and delete everything inside it.
- Open your themes folder, and deleted every theme you are not using.
- Wait 72 hours (Set a reminder or timer), then add the domain back in the control panel.
Since you have a custom domain, you don’t have to worry about it getting stolen by someone else.