There are tons of ways out there to strip minitures (both metal and plastci) and tons of products that will do the job.
Some are better than others.
This is what I use to strip any minis I have. It will work on plastic as well but it really excells at metal. I've used it on models that were painted years ago and it had all the paint off in no time at all.
Spray this stuff on, let it sit for about 20 minutes and then scrub with an old toothbrush. Repeat if necessary.
It has no horrible odor, quite the contrary actually so it can be used indoors without worries. It can be picked up at Walmart for less than $3 a bottle.
The only downside is that it will dry out your hands if you work with it long enough.
Since it's a gel, it can be used to strip certain portions of a model as well and leave other area untouched which is a great feature if you find yourself needing to do it.