The answer to 'how to unclog drain trap' is to remove the trap and clear any debris or blockage. First, place a bucket underneath the trap to catch any water or debris. Use pliers or a basin wrench to loosen the trap and remove it from the drain. Inspect the trap for any buildup or clogs, and use a wire brush or plumber's snake to clear it out. Once the trap is clear, reattach it and turn the water back on to test the drain.
If the clog persists or you are unable to remove the trap, it's best to call a professional plumber. They have the tools and expertise to safely and effectively clear a stubborn drain trap clog.