Can you book and check into a hotel with a signed parents?
No. You cannot used a signed permission slip to check into a hotel if you are underage. Renting a hotel room is not a school trip. You could have written the slip yourself. Also, you would need a credit card to rent a room. Most hotels would simply refuse to rent you a room. There might be a few who would rent a room to your parents, if they are there in person, and allow you to stay in it without them, but I would think those are few and far between. Any hotel that would let you do what you are asking is, most likely, a place for drug users, drug dealers, and prostitutes. Not anywhere you would want to have a romantic evening.