You must be in the Drawing Board Mode to delete a member.
If you want to delete more than one member at a time, use multiple selection, then click the Delete button.
The Delete key on your keyboard performs the same function as the Delete button on the toolbar.
When you delete a member, all with higher are re-numbered to fill the gap.
You can also remove a member from your by erasing it.
If you accidentally delete a member, click the to restore it.