@Sophie--And-Anthony-0
Howard seems to have jumped in at the deep end... without even inquiring if these Guests are USA citizens or foreigners (i.e. on tourist visas)? In the latter case, it is most unlikely you will be faced by 'squatters'.
I have hosted for 6 years near 400 bookings and my kitchen has always been available. Very occasionally I get the kitchen hoggers, but it's so rare that I haven't contemplated revising my policy or amenities.
I believe there is no substitute for a polite face-to-face dialogue with the Guests, and no amount of advice you might receive from other Hosts will change that necessity.
In case you can't reason with the Guests, you have the option to request they leave and find another place, in which case you will be obliged to refund the remainder of their stay.
If that doesn't work, contact Airbnb to dialogue with the Guests.
Best Wishes.