Depends on the plastic. For example methylene chloride based stripper is ok on polypropylene but will corrode ABS. Find out what the plastic is then Google "chemical compatibility". Do a test first but otherwise you're looking at mechanical abrasion. If you have to rub the thing down anyway, might be better off finding a compatible paint and just going over the top
Why remove it if it's ok just sand down lightly and spray under coat and top coat this does depend on what you are doing and the finish required I'm not a sprayer but have done a few bikes once my own tzr 250 plastics that was done with 2 pack looked very Good at the end that was years ago I think I paid for plastic primer to do that
More recent we done my sons mini moto and that was done with pound land paint and did look ok but not great only in 2 places that was sanded down to the fiber glass when it was sprayed there was a very little bit of pickling but as was a mini moto the bike got done for the cost of about a 5er all in
Edit just seen the last comment but what I said still should help and I would prob add an orbital sander to get the paint off
You can use bicarbonate of soda as a blasting media. Harmless to the environment, washes off with water, doesn't damage soft plastics.
I suspect that if the paint doesn't want to come off, you'd be better off feathering the edges on whatever remains rather than trying to strip it entirely and just paint over it.