why can’t I remove this part? I have no idea. Because the hand covers too much part of that character?
I have a queation. If we have big motion blur of object which covers a lot of part of object which is required to be removed, how to solve this?
I got this horrible result. I tried to set + motionblur value. but it cannot blend the edge.
Use cleanplates for tattoos, and you’ll need to overpaint the area on your cleanplate to account for any tracking drift or occlusions. So paint over any FG objects with what should be in the background.
I am still confused, sorry. Is there any tut for reference?
Sure! I recently did a webinar with tattoo removal. You might find it useful: https://vimeo.com/271888194
Yeah I almost done all of your webinar. 
I was considering about that tut you sent but there is no objects (FG) covering tattoo, especially for the objects (FG) with motionblur. The motionblur part is transparent so that you can see the BG (tattoo). How to fix this motionblur extraction with non artificial transitions?
Ah, for occluded objects I actually recommend insert instead of the remove tool. Boris FX | Mocha Pro: Patching & Removing Obscured Objects with Insert Module