I've checked with the rest of the staff and because we're switching the main domain to be an addon domain, it's best to do a full account reset so the domain switching doesn't break anything on your account.
I've now reset your account, and you should receive an email shortly so you can take the next steps to recreate it. Please make sure to enter the domain you want as your new main domain.
Once the account has been recreated, let us know and we can then add the other addon domains and the subdomains you wanted.
I made a backup before the reset, so if you discover you need any of your old files, you can download the backup here: https://heliohost.org/backup
If you're not sure how to extract the backup files, please follow our how-to guide here: https://wiki.helionet.org/Account_Backups