View source for MM DELETEITEMBYPOS

 #define MM_DELETEITEMBYPOS 0x01f1

Delete a menu item by its position.

; mp1 : position of item to delete
; mp2 : unused

Returns the number of items remaining in the menu.

This message will only delete an item in the menu specified. It also
destroys any submenu windows and deletes the bitmap associated with
the menu item if the bitmap was not created by the application.

(Source: newsgroup)