i've only read like the first 10 posts but oh well.
first off, are you a junior? it seems like it cause you have 7 classes and you're worried about your class...
anyway, a few things must be considered: what university are you planning on attending? how will dropping this late into the quarter affect your transcript? will they simply put a "W" for withdrawn, or will they fail you? i'm sure there are other questions, i just forgot them right now 😛
if you are a senior, do as you like. if there's a minimum gpa you need to keep, drop it.
about not taking the AP course, yea, you're not required to take it. i was probably the only person in my entire AP US History class that didn't take the AP class my junior year...it was assumed that everyone took it but they didn't check i guess. even if they did, i had the right not to take it. it was my only C, too, so when i applied to universities, i listed as a Senior year class and not a Junior year class, so i didn't have to list my grade for it, either. if i was asked why i did this, i was going to say something like "i planned on taking the AP test my senior year, so i thought it was supposed to be listed in my senior year course section because that is when the test was going to be taken." might be something for you to consider if you finish the semester but don't take the AP course?