The Moen faucet aerator is slightly different than a standard faucet. It comes in a one-piece component, rather than several separate pieces. This makes changing the aerator less difficult because you do not have to figure out what part goes into the housing first. Removing an aerator from a Moen faucet requires no tools. A seal between the aerator housing and faucet helps prevent the housing from being "stuck" onto the faucet, as well as providing a seal against leaks.
Hold the end of the faucet spout in one hand and grasp the aerator housing firmly with your fingers. Turn the aerator housing counterclockwise and remove it from the faucet.
Pull the O-ring off the tip of the faucet spout with your finger. The O-ring prevents leaking between the housing and the faucet. Set the O-ring in a safe place until you are ready to reinstall the housing.
Turn the aerator housing upside-down in the palm of your hand. Push the screen down slightly with your index finger to pop the aerator free. The aerator is the black plastic piece with the white top.