This is a scam. If you gave them access, you gave hackers total access to your computer.
At this point, the best course of action is to factory-reset your computer in an attempt to remove whatever they have installed and block them from connecting to your system again.
My recommendation would be to use another computer to download the Windows 10 Media Creation Tool, which will help you create a boot-up USB thumb drive, which you can then plug into the hacked computer and reinstall your system fresh and clean, as if you just brought it home from the store.