What subfields in computer sciences may one study without learning Object Oriented Programming?
Depending on where you study, you might be able to get a CS degree without Object Oriented Programming, but the chances are slim. Most degrees would require you to take some programming courses using some general purpose languages along the way, and that will often be Java, C++ or similar, and there you have OOP. Hard to avoid.
But that's good for you, because if you want any job outside university, and you have not a clue about OOP, your chances are practically zero to get any job.