This is your daughter's first experience with learning how to set, and maintain, boundaries. Moving her to another school would of course be an avoidance of this learning experience, and be very bad for her growth. It should not be considered unless the other person legitimately cannot respect the boundary setting, and all other routes have failed (including, as some have pointed out, involving other school officials.) But all of this is untested as of yet.

Step one, your daughter needs to set a boundary with the friend. I.e. "I want to be your friend, and love hanging out with you - but this subject (your crush on me, your desire for me) is off limits moving forward. It won't be mentioned, it won't be discussed. It's a form of pressure being put on me, it's uncomfortable, and if we're going to continue to be friend - it has to stop. If you're truly my friend, I expect this request to be respected."

Step two, is to enforce the boundary. This means, if the friend starts doing it, a single reminder, "This topic is off limits. Please stop." If the friend does not stop, then your daughter needs to end the encounter. Ask her to leave, hang up the phone, go to class, come home, whatever. The boundary must be enforced if it is to be respected. This will be hard, because it may also require her to step away from her other friends also present. But if they are friends, they should have her back - and also realize that the pressure being put on her is causing them to miss out on her as well.

Step three, if the friend cannot maintain the boundary, your daughter will have to end the friendship. This will be extremely hard, since she hangs in a group - and it may mean less (or no) contact with other friends who also hang out with the friend in question.

If it STILL doesn't stop, the school needs to be informed, as it really is a form of harassment.

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This lesson in boundary setting is NOT a trivial experience for your daughter. In a world of #MeToo, this first (very difficult) experience with boundary setting and maintaining will help her learn to do it throughout her life - regarding boys in college pressuring for sex, bosses pressuring her, boyfriends pressuring her - and people in general trying to pressure your daughter to do things she's uncomfortable or unwilling to do.

If she starts running from this (swapping schools), she'll be running her whole life. she can't quit her job every time someone starts pressuring her.