I've massively over-sprayed my models! Help!
Yes, acrylic paint can be safely removed, and quite simply too. The basic process is to dunk your models in a solution of household cleaner, watered down if you like, and leave them in the bath for a few hours. The paint turns into a kind of slimy goo, which you can then scrub off with a toothbrush and toothpicks.

In the US, Simple Green All-Purpose Cleaner is the standard recommendation. In the UK, diluted Dettol (a common disinfectant), has been shown to be effective.

Somebody actually did a comparison of different cleaners for this very purpose. He actually found that oven cleaner worked best of all (easy removal after an hour), but also reported positive results with Simply Green (although interestingly, not 409, which serves a similar purpose).

Degreaser or brake fluid are other possibilities, but these are nastier and harder to assess, since they come in many variants. For safety, I'd stick to surface cleaner, or oven cleaner if you have a test model you are willing to potentially sacrifice (if you've ever cleaned an oven, you'll be well aware that oven cleaner is viscous stuff!).

Methylated spirits and so on are best avoided, as these can erode your models over time.