Having multiple antivirus programs running at once can cause system instability

You’re right—two real-time antivirus engines can inspect the same files and network traffic, which can cause slowdowns or freezes.

Pick the one product you want to keep. Uninstall the other from Settings > Apps > Installed apps, restart, and then use that vendor’s official cleanup tool only if its services or drivers remain. After rebooting, open Windows Security > Virus & threat protection > Manage providers and confirm exactly one antivirus provider is active. Microsoft Defender normally turns itself back on automatically when a third-party product is removed, so you should not be left unprotected during the change.

I’d also remove any leftover browser security extensions from the old suite. Avoid registry cleaners or third-party “AV removal” downloads. Which two products are installed? The exact cleanup steps can differ by vendor.