GPS location faking is not allowed. To get rid of the alert, do the following:
- for devices using Android version 4.2.2 Jelly Bean or older - go to Settings -> Developer options -> Turn off Allow mock locations
- for devices using Android version 4.3 Jelly Bean (API level 18) or newer - disable any third party location mocking applications.
If the problem still persists, please restart your device.