How to Remove a Sink Trap
Unscrew the metal slip nuts a half turn or so, so that you can finish loosening them by hand.
To protect the chrome finish on the slip nuts, wrap tape around the jaws of your wrench or pliers. Plastic traps have slip nuts that you can usually turn by hand. Some traps have a clean-out plug instead of slip nuts. Simply remove the plug and allow the blockage to spill out.