What should I do!!!!...Im not sure if I should drop my Precal class

I am a senior and I am taking pre calculus.....I dont need to take this class to graduate high school..I had finish 3 yrs of math which is all I need but im taking it because I know its good for college but if I Fail I wont graduate at all! and its hard to pass I have an "F" and it hasn't got to the hard part yet..Im not so positive about passing...I feel like I have a 50% chance that I'll pass..I dont know if i should risk it and stay in the class or if I should just get out before grades are due because it will affect my chance of getting my high school diploma....HELP!!!!!!!!!