Unfortunately, it appears you were scammed into letting someone untrusted remotely into your computer. It is one of the worse types of compromises, and exposes you to a host of continuing risks.
Scammers (you have granted suspicious remote access) have been found to use a combination of legitimate tools and hacker tools (RATS) to maintain a direct connection to your device and/or con you with ... Scans will not necessarily remove or find their compromises; to the safety, security, and stability of your computer.
After allowing untrusted individual(s) direct/remote access to your computer from a Tech Support scam, you should do a Reset(Remove Everything) or Clean Install; change All your passwords from a safe device (or this one after a Clean Install), talk to the Fraud Dept of your Financial Institution to report them and recover money, if spent (tell them you were scammed with a fake tech support scam), and watch your bank acct(s) & credit cards closely.
Know what you were subscribed to, by the scammer! And make sure you cancel & report to your financial institution(s), all the Credit Card(s) you may have used.
▓►Avoid a post. Backup your data.◄▓ -{from the signature of Bruce Hagen(MS-MVP)}
Make sure your data is backed up, and 'Win 8.1 Reset(Remove Everything)' and/or Win8.1 Clean install, then install your desired AV solution (if any, besides the suggested Win8.1 Windows Defender)....
Help: I Got Hacked. Now What Do I Do?
https://technet.microsoft.com/en-us/library/cc700813.aspx
Verify yourbackup ('FileHistory' and/or verify your OneDrive Sync).
Create the media from a safe computer.
https://support.microsoft.com/en-us/help/17085/windows-8-restore-refresh-reset-pc