Welcome to the community! Right now in monday.com you can go into the Admin profile view and deactivate the user. This will not “remove” them from the boards that they are assigned to, but it will stop the user from having access. To add someone to monday.com board what I might suggest is leveraging the “board ownership” tab in the Users Menu (Admin Panel) to add someone to all of the boards on monday.com that are assigned to someone else.