Mobile APIs have the handlers return a token
This token can be removed in the removeListener

You have to go to the JS API docs to really figure out how this is done. The real way to do is to have a reference to the callback handler. It would important to show how {{removeListener}}works on the main website.

const callback = function(changes){ 

}
realm.addListener('change', callback)

// later
remove.removeListener(callback)