top layer in spiral vase

[NinjaAtWork]

Hi all
please have a look at the end of this spiral spring in below:
https://www.universalcycles.com/images/products/large/81314.jpg

i need to make top layer of spiral vase in clay print to finish smoothly which the last point cant be seen or be find easily .
by decreasing both extrusion and fixing the height of last layer to prevent big elephant foot step and make the z height.
how this can be done please?
thanks