how to unset firebase cloud functions environment variable

I have tried using command line functions:config:unset es.tipsinstitue.type as it is given here Environment Configuration. But this does not work for me. It gives me following exception.

 The filename, directory name or volume label syntax is incorrect.

Please help me.

How can we stop cloud function?

You cannot disable a function. Just comment the function body. It would be a good practice to log the call in the console and then return null so you can keep track whenever the function is invoked.

Don't know whether it is documentation bug or not. Use firebase functions:config:unset es.tipsinstitue.type instead of functions:config:unset es.tipsinstitue.type. This will remove your environment variable