sihost.exe is a program which is most likely legit. So, if sihost.exe is on your PC, it is most likely ok, and will NOT cause problems. Even if your PC is virus-free, it is still recommended to use a good antivirus with a good track record, in order to defend yourself against viruses and malware.
Usually, the default filename and folder where the application is stored is
The MD5 fingerprint for this file is 0c9644276843d331a61a0900c1c13280.
This program is NOT registered as a Windows service. This is good.
sihost.exe appears to have something to do with Windows SFC (System File Checker) or Windows File Protection.
This is a x64 executable. It runs using the full capacity of modern CPUs.
sihost.exe has a digital signature. Today the large majority of legit software applications are digitally signed.
The digital signature extracted from sihost.exe checks out perfectly. This is very good.
Digital certificate name: Microsoft Windows
Certificate's issuer name: Microsoft Windows Production PCA 2011
This program does NOT have an uninstall command stored in registry.