this is going to be a noob question, I've tried googling and tried finding videos but didn't find anything so don't hate.
Does anyone know how I would remove these sideskirts? The car did have a body kit that the previous put on it. Will I need new fenders and quarter panels?

 

Since those were molded on, you're going to need to do bodywork after they are removed. Depending on if the previous owner used fiberglass or bondo, you're going to have to remove the material somehow. Hopefully the sideskirt wasn't attached crudely, but I fear that deck screws or something of the like were used.