-k : The "verification key" or passphrase required to bypass tamper protection .
Even with the correct syntax, sentinelctl.exe unload can fail. Here are the most common errors and their solutions. Sentinelctl.exe Unload
This is where the command sentinelctl.exe unload comes into play. What is Sentinelctl.exe? -k : The "verification key" or passphrase required
sentinelctl unload -t "your_site_token"