In some case items need to be Deleted from a To Do List as they are no longer required. The only way to delete items from your To Do List is through the 'Delete' option in the My Items section on the ribbon.
After clicking on the option in the ribbon a select form opens to show the current items for the active list, now select the item or items to be deleted and select 'Delete' to remove them from the list. This action CANNOT be undone so you need to be sure that the items should be deleted from the To Do List before confirming the delete.