Hi Safiqul, there is a retouching option in Helicon where you can choose a single source image from all your images after you have stacked them, and then just use a brush to retouch the areas that have artifacts. You can do this as many times as you need to.
So if you have an area with artifacts, you choose an original source image that is in focus for that area and just brush that part back into the rendered image.
I probably do not explain it very well here but it is pretty simple to do, it just takes time.
This video shows the method: