Before 4.14 deleted folders were gone and came back once you opened up the editor again. Now after the update the folders do no disappear at all when attempting to delete.
Is it happening only to me?
Delete those folders from your “…]\Unreal Engine 4\Unreal Projects” folder because sometimes UE4 keeps them alive…
They will be deleted as of 4.14. They finally added that “Feature”
I keep getting this problem in 4.19
make sure you rightclick on the folder and fix redirectors, you can the delete the folder nicely.
^ This. Those folders probably still contain redirectors. Do not delete those folders until you have fixed up redirectors within the editor.
Actually it would be quite helpful if the editor automatically fixes redirectors on folder deletion. Ill do a PR for that 
that would be super helpful 
i always assumed it was some technical limitation or performance issue that made it impracticable to auto fix re-directors when deleting or moving folders.
Fixing redirectors can sometimes take quite a long time, which is undesireable - so it’s better to run them as-and-when the user wants to. A reminder wouldn’t go amiss, however.
I’ll take that into account 