APEX

I need help with my interactive grid, can't figure out how to delete only the one before last row of editionable grid in a table after clicking a button.
One before last row because last row is a row with summary where I am gonna use:

defaultGridColumnOptions = {
    aggregates: ["SUM"]

I need a functionality that will allow users to delete only the one before last row in an IG, no matter which row they select in an IG. Adding new rows should work the same, adding new rows as one before last row position of an IG.
To create buttons I used below code:

function(config) {
  let $             = apex.jQuery,
      toolbarData   = $.apex.interactiveGrid.copyDefaultToolbar(), // Copy the default toolbar
      toolbarGroup = toolbarData.toolbarRemove("edit");
      toolbarGroup = toolbarData.toolbarRemove("selection-add-row");
      toolbarGroup  = toolbarData.toolbarFind("actions3"); // Get the group you want to put your controls into
   
    toolbarGroup.controls.push({
                            type: "BUTTON",
                            action: "selection-add-row",
                            label :"Add row",
                            id: "add_info",
                            icon: false,
                            iconBeforeLabel: true,
                            disabled: false
                        });
    
    toolbarGroup.controls.push({type: "BUTTON",
                            id: "delete",
                            label: "Delete row",
                            icon: false, //or icon: "icon-ig-delete"
                            iconBeforeLabel: true,
                            //iconOnly: true,
                            //hot: true,
                            //class: "a-Button-label"
                            disabled: false,
                            action: "selection-delete"
                         });

    
  config.toolbarData = toolbarData;
  return config;
}

I created an application:
https://apex.oracle.com/pls/apex/f?p=4550:1
Workspace: ig_buttons
User - TEST
Pass - IGtestAPEX