If your faucet aerator is not removable, it’s likely because it’s stuck due to all the gunk that’s accumulated in that area over time.
To clean it, it’s best to remove it first. First, place a towel or a rag on the faucet cap. Turn the cap counterclockwise using a wrench or pliers positioned over the rag.
Once the cap is loose, remove the pliers and the towel and unscrew the aerator using your bare hands. Remember the positions for each piece of the mechanism, as you have to put them back in that exact order. Proceed to clean the aerator as you normally would.