I have Spybot Search & Destroy + AV Professional (Settings on a PC with Windows 10 Pro.

I would like to use Windows Defender Real-time Protection. However, I can't because Windows says "You're using other antivirus providers". The only other antivirus Windows shows is Spybot.

In the Spybot Start Center, I checked "Advanced User Mode", then clicked "Settings" & selected "System Services". I tried to stop the Spybot Security Center Service, but the Stop button is greyed out and inoperative.

What can I do? The only thing I've found that works is to uninstall Spybot. I don't want to do that because I will have wasted my money buying the Professional version.