Hide delete button

Hi All

I am trying to hide the actions menu and delete button from the ribbon. I am usng the JS below which works fine when I try it in browser console but does not work when I add this to Nintex form custom JS section. Any idea why this would not work and also if there is another way to hide these buttons/sections?

NWF$(document).ready(function(){

var hidedel=document.getElementById("Ribbon.ListForm.Display.Manage.DeleteItem-Medium");

hidedel.style.display="none";

var abc=document.getElementById("Ribbon.ListForm.Edit.Commit.Cancel-Large");

abc.style.display="none";

var hideactions=document.getElementById("Ribbon.ListForm.Display.Actions");

hideactions.style.display="none";  

});

Thanks