This article will explain how you can change your personal details through cPanel
Login to your 123-reg VPS cPanel WHM interface.
Click on the Account Functions button in the main window.
Then click the Modify an Account button.
Then select the account you wish to change, then click the Modify button.
Edit the information you wish to change.
Then click the Save button at the bottom of the page.
Your Personal info will now have been changed.