Support question - how to close / cleanup existing vorpal instance

Say we want to create a new instance of vorpal - how would we clean up an existing instance?

aka,
I have code which will start "a new vorpal" instance. How can I close / cleanup any existing vorpal instance?

I assume this involves:

`process.stdin.end();`

As an aside - It would be great if this project could be updated with TypeScript then the API would be easier to access.