We cannot change domains directly like this, but what we can do is add and remove. I've added the scoobverse one from your request here.
I have now removed the smurmel one from your account. If you want the content from smurmel to be on the scoobverse web address, you would need to re-upload the files inside Plesk.
Please note there is a risk of data loss when domains are removed, since the folder for the domain inside Plesk will be deleted. I made a full account backup for you before I removed the domain, in case you need any of the 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