XmListDeleteItem(3) on Linux
The text 552d82c66115, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A List function that deletes an item from the list "XmListDeleteItem" "List functions" "XmListDeleteItem"