Unfortunately, we can not, as it is right now, "Remove" them so that nothing comes out to you, But! there is an option to stop the flow.
The way to do this is to go under users and disable them from inside our portal.
However, this will mean that the account is deactivated, and you must contact us to get it unlocked again.
We are aware that this is not a feature we have yet, but in the near future (before August) we will look at having this as an opportunity.