How do I remove bathtub drain screw?
I use large needle nose pliers if I don't have a drain wrench. The pliers need to be opened and in contact withthe outside edge of the metal cross member. Turn counter /anti clockwise. These parts are usually brass and or plastic so they don't usually rust. If the assembly starts deforming with needle nose a drain wrench will be needed drain wrenches slip over all 4 points and provide more force without damaging the existing flange. Here is an example One of the less expensive ones I saw with a quick look.