This app can be set as device admin to prevent removing it without entering the devices Passcode first.
No security policies are used.
This feature only works if the devices admin policy is set to request passwords when removing apps (Mostly found in businesses or shipped with parental control apps)
DNSChanger won't actually use these rights.
DNSChanger has to be removed as device admin before trying to remove it from your phone, come back to the settings to do so.