these game engines are quite complex. you need to leave them be with the file structure they have else is guaranteed you will have a really bad time.
maybe your computer has a second drive? you can have the engine and the library content on a different drive than the main one.
I didn’t tried to have the engine on an external drive but the library content should work
As reference unreal 5 is 50Gb on my system.
you can also cut and paste in and out manually the folders from the library to have them as a backup. Or just have them in the library folder only when needed.