Note: the option to remove or delete users from your team is available to Business and Enterprise subscribers.
If you are wanting to stop someone from participating in a Personal Storm, as a Storm Administrator and/or Team Administrator your option would be to close the Storm making it read-only. You can then start a new Storm without that participant.
Note that if you reopen a Storm you will allow the users in that Storm to actively participate again and billing charges will apply in ALL paid subscriptions.
Also See: