var arr = [1,2,3,4];

    console.log(arr[arr.length -1]); // get the last element
    
    arr.pop(); // delete the last element
     
         (or)

    //other way for deleting the last element
    console.log(arr.splice(arr.length-1, 1));
    
    console.log(arr); // [1,2,3]