That is still not a memory leak. A memory leak is untracked memory that cannot be deleted. If you have 64GB of RAM and no limits set, unreal will use it just like any other program would.
It doesn’t matter if you close the skeletal mesh editor, the asset has still been loaded along with anything it uses. It won’t be spontaneously unloaded until the editor needs to open something else and decides that object is no longer relevant for some reason. Closing an asset editor doesn’t unload the asset. If you load a blueprint that references meshes, materials and suchlike they all have to be loaded as well.
What’s the point in having that much RAM if you don’t want applications to use it? The question you should be asking at this point is how on earth do 200 skeletal meshes have so many linked assets to achieve a whopping 64GB of memory use?
If you try to open the Kite Demo - it uses nearly 24GB of RAM because that’s how much the loaded assets cost to load.