To remove members from a board, open the "Board Member" menu by clicking on your avatars next to your board’s name, or by clicking on the member’s tab in the left-hand navigation of the board.
Once in your member directory, click on the member’s name that you want to remove from the board. Then click the ellipsis drop down over your selected member’s name. If you are the "Owner" of the board, you will see the "Remove" option. Click "Remove" then confirm their removal.
Repeat this step for all people you want to remove from the board. You can remove pending or active people on the board.
When a person is removed from a board, they will be removed from any tasks they were assigned to. All other information associated with the person will remain on the board. This information includes tasks, comments, file attachments, sub-tasks, start dates, due dates, activities, and descriptions.
Learn more about Changing permissions on a board
Learn more about Changing your board owner