Theoretically, yes.
But why would Philip V necessarily want annulment ?
You mentioned the risk of war and you are of course right but Europe was already in a general war at that time, and precisely about a succession matter : in the HRE for the imperial crown and for the Habsburg kingdoms and principalities. It was the war of austrian succession.
So if the french are already at war against Great Britain, Habsburg Austria, Russia, the Netherlands, and are allied with Spain, Prussia and Sweden, well there's no threat the opponents to such a succession could use to convince Louis XV from not playing this card if he wanted to.
The treaties of Utrecht were not necessarily eternal. They lasted only if Britain was able to gather an alliance that could deter the Bourbons from denouncing the treaty.
And in 1746, the european powers were exhausted and close to bankrupcy, Britain included. So I think this would have been an opportunity for a master coup for the Bourbons.