Just ignore it CoolBreezeTG6, it's a spurious error due to the fact that the Malicious Software Removal Tool currently has no purpose running on a Windows system running in S mode.
Unlike others, I don't believe this will ever be fixed, at least not until Microsoft either needs to provide a working version of the MSRT because a malicious actor found a way around S mode or more likely a major Windows update removes MSRT from such systems
permanently.
Of course this is frustrating for non-technical users, but letting it get to you is your own fault. Once I realized MSRT wasn't required with S mode, I just stopped worrying about this message entirely, it's really that simple.
Rob