If you do not have a file dependent on kite demo, it may be better to delete it with Explorer.
Or, I think there is a way to migrate Assets related to your project into a new project.
Actually you can delete in folder but if there is any reference it will be a big problem for you 
Is there a way to delete assets from outside unreal engine? (i want to delete kite demo since it takes more than 10 hours the package a project)
And when i want to delete it inside the editor my comp freezes 
If i try to delete it inside unreal it freezes
You said earlier it takes 10 hours to package? You might just have a very slow system, I would wait and see if it unfreezes after you give it time.