Windows 10 Pro computer comprised

Please don't laugh I pay great attention to keeping my computer safe, but really screwed up this time. I got a$499.99 subscription charge from Norton however I ended up indirectly allow the tech to remote my computer while I was watching bad idea. You know the rest had multiple charges on multiple cards! In the aftermath I was able to cancel cards etc. I am running BITDEFENDER and wasn't seeing any errors popup. How would if one of my brothers could suggest some things that I could install, run, clean or negate anything residual in the code that would enable remote control or gain access again.