If you are an owner of a vBulletin forum and have a troublesome user that needs to be deleted, then you can do so by following the steps below:
First, log in to your vBulletin admin control panel.
Second, click the “Users” menu, then click “Search for Users”.
Third, type in the user’s name and click the “Find” button.
Finally, click the drop-down menu adjacent to the user’s name and select “Delete”. Click “Yes” when prompted to confirm your decision.