What can I do to prevent it from starting without removing the battery or seriously damaging my car?

Probably the easiest is to remove the electronic fuel injection relay. It's in the fuse box under the hood. The starter will still crank the engine if you find the key, but the engine won't start and run.

A different way is to disable the starter system. You can do that by removing the starter relay or the "AM2" fuse. Those are both in the same fuse box. The engineers appeared to be unable to use the same terminology on the diagram and in the fuse box, so if your starter relay isn't labeled as such, go for the fuse instead.