What should I do about my schedule second semester of senior year?

So I was accepted to Northwestern early decision, and I want to drop a course on my schedule in high school. Their website says that your senior year should be the hardest and most challenging, but I’m worried I’m not doing enough, though I’m probably over reacting. Anyways, first semester (which is going to be over soon) I had Composition I (a college class), american government, choir, english for publication, band, macroeconomics, spanish IV, and PE. My school doesn’t do AP classes, and none of my college credits will transfer so I don’t think it’s worth it to take online college classes. Anyways, second semester I’ll have Composition II, choir, band, microeconomics, english for publication, and sociology. I want to drop spanish IV because I know I’m not learning anything and I could leave early from school and get more hours at my job. However, I’m kinda worried that I won’t have a heavy enough course load. Is this something that they would rescind their admission for or am I just completely overreacting?