The example scenes folder can be excluded (though it does contain some nice scripts which you may want to use).
If you enable ASTAR_NO_ZIP under the Optimizations tab you can delete the Pathfinding.Ionic.Zip.dll (though this will make stored graph data larger, and you will have to reconfigure your graph settings).
After that it will be trickier to exclude larger parts of the package. You could probably remove most of the RVO stuff, but there may be stray references to it from other scripts.
All licenses for 3rd party packages are in the AstarPathfindingProject/Plugins directory, but they should be very permissive. This package can be used in any of your own projects as long as you don't distribute the source code for it or resell the package itself.
Looks like a cool game!
Let me know when you have released it and I can add your game to the list of games that use the A* Pathfinding Project on the package website if you want!