I am a junior college student majoring in tourism management. I was assigned to a hotel as an intern by the school. If I quit my internship before it's over, can I get a diploma?

It depends on how your school and hotel talk. Some are purely internships. If you don't want to do it when the time comes, you can go back to school or find your own internship place, and then you can have an internship appraisal. Some schools and employers have an agreement that they can't resign during the internship, otherwise they won't give you a diploma, so ask your school, but the latter is unlikely.