How can I clear memory spaces such as "Texture Memory Used" and "StaticMesh Total Memory"?

I add my Level into the World using the UWorld::AddStreamingLevel method and load it into the World with UGameplayStatics::LoadStreamLevel . However, after unloading the Level using UGameplayStatics::UnloadStreamLevel and removing it with UWorld::RemoveStreamingLevel , the memory is not released, even though the Actors in the Actor list are indeed cleared. This situation persists, and the memory remains occupied, as if these Levels are still present in memory. What can I do to properly unload them?
Before loading:


After unloading: