It is not currently possible to delete a user account.
But if you email us from your master account (this is the account with which you first signed up) and let us know the email address of who you would like to have removed, we can do it for you.
Please note - deleting a user also deletes any calendar events created by and assigned to that user.
No other records get deleted.
If you need or wish to keep these calendar events, we can simply remove access to the apps and the website for that user instead and remove the user license.