When a team member and Milanote user leaves your organization, there are three things you might need to do. It's best to do these before the person leaves your group.
Remove them from your Team plan (if on a Pro plan)
Go to the Settings menu (in the top right of the screen)
Choose View billing details
Choose Manage team
Click the Remove link next to their name
Remove them from any shared boards
Go into each board that has been shared with the person
Click on the board Editors in the top right of the board
Click the arrow next to the person
Click "Remove them from this board". This will also remove them from any boards within that board.
It's not possible to automatically remove someone from all shared boards. Learn how to organize your teams boards in one place so it's easier to control access to shared boards.
Take ownership of any boards they currently "own"
Before the team member leaves, ask them to 'hand-over' board ownership to another team member. Here's how they can change the board owner
Go into a board where they are the owner
Click on the board Editors in the top right
Click the arrow next to someone else in the list
Click "Make them the owner"
You can then also remove the person leaving from the board. This will remove them from any boards within that board.