If the extension is greyed out or cannot be turned off, it is controlled by Windows Group Policy. Standard users typically cannot disable this without removing the underlying policy.
If the profile is locked (red "Remove" button), you must use the terminal (requires root): disable symantec endpoint protection chrome extension
Log in to the console. Navigate to Policies and select Intrusion Prevention . Edit the active policy and locate the Windows Settings tab. Uncheck the option for Enable Browser Intrusion Prevention . If the extension is greyed out or cannot
sc stop smc sc stop ccSvcHst