Removes the element found at the index. All elements stored after the given index, are moved down by 1.
This also supports negative arrays, which work back from the right side of the array.
names = [ 'Ashley', 'Jenna', 'Graham' ]
// names now contains 'Ashley' and 'Graham'
names.deleteAt( 1 )
// names now contains 'Ashley'
names.deleteAt( -1 )