Kitchen Faucet

[bluedog103]

Does anyone know how to remove the aerator from the kitchen faucet? We have a new designer. The faucet neck has some kind of black button on the rear of the neck just above the aerator. I don't know what that is for. The aerator seems to be seated internally in the neck but I can't get it to loosen. I don't want to force it and break something.
Thanks