You can register for a new account with the account name you would like to use.
Afterwards, backup your data manually on your previous account to restore your data in your new account.
There are two ways of saving a manual backup in Ragic, you can either back up your entire database that includes your data as well (saved as .ragicdb format), or use the "Backup database definition only" option to save the design elements without your data (saved as .ragic format).
You can restore either type of backup on your new account.