No, you paid for the papers not your teachers. Teachers tend to overrate their authority over you, they shouldn't but in the end if they really didn't care, they wouldn't recommend any level for you. Have a think through it and if you decide to pull off your desired level ask yourself if realistically be able to do it in that level. I'm the same with physics but my teacher told me that obviously it's my choice, and he recommended ordinary level..I'm still gonna ignore their advice tho since I'm gonna have 5 days and a half to study for it.
my teacher and headteacher tried to for my irish, but at the end of the day, you get to choose! if you have dropped down , make sure you have handed in a letter, or bring one asap to whoever is in charge of the exams in your school (mine's the deputy head) making sure they are aware. they may not allow you change on the morning, unless you have said letter (we had this in irish this morning where someone decided an hour before the test)
so no, you get to make the choice 100%