delete the last three history state

@Mohamed Hameed21513110 

Try the following code, it has not been exhaustively tested, however, it would appear to do what you have requested:

/*
Delete The Last 3 History States.jsx
https://community.adobe.com/t5/photoshop-ecosystem-discussions/delete-the-last-three-history-state/td-p/14022026
v1.0 - 21st August 2023, Stephen Marsh
*/

#target photoshop

var theStateLength = activeDocument.historyStates.length - 1;
if (theStateLength >= 4) {
    // Perform the tasks 3 times
    for (i = 0; i < 3; i++) {
        // Select the last history step
        activeDocument.activeHistoryState = activeDocument.historyStates[activeDocument.historyStates.length - 1];
        // Delete the active history step
        removeHistoryStep();
    }
    alert("The last 3 history states have been deleted!")
} else {
    alert("Script cancelled as there are only 3 or less history states!")
}

function removeHistoryStep() {
    function s2t(s) {
        return app.stringIDToTypeID(s);
    }
    var descriptor = new ActionDescriptor();
    var reference = new ActionReference();
    reference.putProperty(s2t("historyState"), s2t("currentHistoryState"));
    descriptor.putReference(s2t("null"), reference);
    executeAction(s2t("delete"), descriptor, DialogModes.NO);
}