No, no te autoriza a quitar los creditos...
Pero por $120 se los podes quitar:
Cita: Branding Free Option - $120 per license
All vBulletin communities must retain the vBulletin and Jelsoft copyright text at the end of every page as per the license agreement. If you would like to legally remove this branding, you can purchasing the branding free option, which costs $120 per license.