hye guys,
newbie here...
would like to ask on how to remove the paint from the plastic effectively?
thanks

Thank you sir,
the material were build from magnesium,
and the stock coat were too thick,
is it possible to remove the paint by using diluted thinner?

disagreed. base color will definitely influence how the top color will turn out. that's why people do pre-shading. 

Vorador, yes it will work. for a better effect, use a white base for the lighter/brighter red, and grey for a darker red.

im not sure what king od spray paint you use, what i said was based on normal spray can cost around rm6-7. why dont u that on a piece of plastic n see the result 
In my opinion(still based on normal spray can, without any aid of professional tools), your 2nd coat will either thick  enough to fully cover the 1st coat, or thin enough to let the 1st coat appear partially, but not uniformly, it means the 1st coat is visible with different intensity on different area. I dont think there is any way u can ensure the exactly thickness  of the paint when using spray can 

if you want to achieve the same effect as the one pic you've shown, you must mix the color. Layering a dark based and second coat of red will be difficult to achieve since you're using a spray can. Difficult to control the paint flow. If you have an airbrush, this would be a breeze..

yea what Noysan said is correct, expect that result only when you have an air brush 
you better take the proper steps, its totally unworthy if you spoil the appearance of the parts just becz a bit of laziness 

Since you are going to do post shading anyway, why dun u just try and see whats the result on a piece of plastic 1st