class GPGME::Ctx

def delete_key(key, allow_secret = false)

otherwise secret keys are deleted as well.
If allow_secret is false, only public keys are deleted,
Delete the key from the key ring. 
def delete_key(key, allow_secret = false)
  err = GPGME::gpgme_op_delete(self, key, allow_secret ? 1 : 0)
  exc = GPGME::error_to_exception(err)
  raise exc if exc
end