You can delete members on the My Team - Members interface.
How to delete members
Click My Team - Members:
1) Check the check box before the name of the member(s) you want to delete, and then click the Delete button above to delete him/her;
2) Select the member you want to delete and click the Remove button.
If the member has unfinished translation or editing tasks, a pop-up window will be displayed to inform you of his/her current tasks. Then you can click the Remove button.