XmMultiListDeselectRow(3) on Linux
The text b8f4f2283ba3, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A MultiList function that deselects a row in the list "XmMultiListSelectRow" "MultiList functions" "XmMultiListSelectRow"