How do you clean the screen that is located inside of the faucet not screwed on the outside

A little special wrench came with the kit. Contact Delta

The aerator is entirely within the faucet and does not show from the outside. The manufacturer provides a plastic "Y" shaped spanner wrench with the full assembly at purchase but if you had a plumber install , bets are that the wrench was not left behind because they throw away all parts they don't use and fail to recognize this is a tool to be left for the homeowner. This can be improvised if you an find an adjustable spanner wrench at Harbor Freight which will remove it by placing the spanner end knobs within the small insets (180-degrees apart), but you'll need a mirror to see these. Otherwise, without a spanner wrench you can use needle-nose pliers in locked open position in the two inserts.

Thanks for your question! The aerator is removable from the inside of the faucet with a wrench that was provided with the original packaging. Should you need a replacement part, please contact our consumer support line.