After experimenting a lot it seems I cannot delete trees that were from the legacy editor from before the latest update, however i can perfectly fine delete newly placed trees.
Also, After I had baked some trees I am unable to delete them, however manually placed trees can be deleted just fine.
Trees that were added by the “bake foliage” tool can’t be deleted unfortunately. I suppose the trees added before the update were upgraded to devkit when the game updated so you have two options:
bake clear, then place trees manually so you can have more control over them
bake clear, then bake foliage again and hope for the best
from what I’ve seen the foliage tool only removes the trees that are selected in the asset browser, maybe try selecting the different russia trees and deleting?
Manually removing individual baked trees and grass will be added in the next update with a new hotkey. By default they are filtered out from the removal brush because there are so many.
EDIT: Relevantly, we’ve just published a FAQ/blogpost that explains how to use various tools, and mentions some of the upcoming improvements to the editor.