Once a name for the link has been created that name will no longer be available. It is going to be first come first serve regarding the names. I would suggesting logging into your dashboard and picking the referral name you would like now so that you may have a better chance at getting the one you want.
Please start by logging into your dashboard at cloud.justpruvit.com. Once you are in your dashboard, click your name in the top right corner and select 'Settings' from the drop down menu. On the next page your profile details will be displayed. On the left side of the screen you will see a button that says 'Referrer Code'. Click that then click the edit button on the next page to change you referrer name to one of your choice.