Create folder ok delete not

it works

public_dir = File.join(RAILS_ROOT, “public/images”)
dir = File.join( public_dir, “#{new_property.id}”)
FileUtils.mkpath(dir) unless File.exists?(dir)

it not

public_dir = File.join(RAILS_ROOT, “public/images”)
folder = “118”
dir = File.join( public_dir, “#{folder}”)
File.unlink(dir)

its not the same ?

I got error

Is a directory -
/home/maugustyniak/workspace/new_bjbpartners/public/…/config/…/public/images/118

sorry never mind its so stupid I think I am tired
dir.delete of course