Toggle the Real-time protection switch off. You may receive a User Account Control (UAC) prompt asking if you want to allow the change to occur. Select Yes. When you're ready to turn system protection ...
Windows Defender does a decent job of blocking malware but lacks many of the protection features found in suites like Trend Micro Internet Security.
Microsoft no longer officially supports Windows 10, so do this if you want to keep using your older PC securely.