One option might be to stick it out, especially if you're definitely not going to end up with lower than a C. Then see how you do in O-Chem II next semester. Obviously this is going to depend on if you think you understand the material or not. That is, if you're getting a C because you don't know what's going on at all, you'll most likely do poorly in O-Chem II and should probably withdraw & re-take O-Chem I again to avoid having the same thing happen again in O-Chem II. However, if you just got off to a rough start but are understanding it now, or there's something else going on, and you think you know enough to go on to O-Chem II, then stick it out.
Getting a C in O-Chem I but an A in O-Chem II wouldn't be the worst thing, and you could always go back and take O-Chem I afterward if you still wanted to try to bring your GPA up (depending on what your school allows for re-takes).
Obviously there are a lot of factors to consider (such as how your other grades look, how many Ws you have already, and your school's policy on re-takes/grade replacement), so no one here can tell you what is best for your situation, but that's my 2 cents for something to consider.