Place macaroni noodles, butter, water, dry mustard, salt and pepper into Instant Pot.
Close lid, close valve.
Cook on Manual for 4 minutes. (If you are new to the Instant Pot, it will take time for the pressure cooker to come to pressure, before the cooking cycle begins).
Use quick release, to release the pressure.
Remove lid and check to see that macaroni noodles are to desired firmness.
If they need to be cooked longer, turn the Instant Pot to Saute, and cook until they've reached your desired consistency.