Please add an option to delete forest pack geometry upon deleting the forest pack object from the scene. This would be a great feature for all people in the Arch Viz industry. I imagine the best approach would be for Itoo to create a "Forest Cleaner" toolbar button which you can use to purge out unused geometry and materials from the scene.
But where do you place your assets ?
If you use the Library Browser, assets are stored in the "forest_templates" layer, and this layer is already cleaned automatically by Forest (when saving scene, or assigning other assets from the library). So this problem should not occur.
Instead, assets stored out of this layer cannot be deleted automatically.
Basically, because once they are not assigned to any Forest object, we have no way to identify them. They could be objects used for any other purpose.
The only way, would be to delete them immediately, once they are unassigned from Forest (as discussed in previous posts). But this approach has several drawbacks, and we prefer to not use it.