I just encountered this same issue with a generated mesh I had created when modeling got moved to a different folder, but the level was still referencing the old path. Upon inspecting the path in the reference viewer it pointed to none, but the link was unbreakable.
I fixed my issue by recreating the asset (could be a dummy asset just has to have the same name/path) so it could find the file. Then deleting it again.
So in you case create the asset:
/Game/VigilanteContent/Vehicles/East_MLRS_Smerch/SK_East_MLRS_Smerch
This should solve the LogStreaming: Error: Couldn’t find file for package.
Now you can attempt to delete the asset again, and this time it will ask you to replace it with the correct reference location or just remove all references.