Hi Carolina--
You can check what menu items are aliased to by looking at editmenu.cf in $ARBORTEXT/lib. In this case, the "Delete Row" menu item calls the "TableDeleteRow" command. If you want to replace table row deletion with your custom function more or less everywhere, then you would use the "alias" command to redefine "TableDeleteRow" so it calls your function instead of the default one. (To see how it's currently defined, you an use the "show aliases" command.)
If you want to add a new menu item, you can use the "menu_add" command to do so. It is pretty well documented in the help center.
--Clay