well, my problem is: I have an application which is set as the device owner of a device (my tablet in this case). I did it from the terminal in Ubuntu, connecting the tablet to
you can use the following ADB shell command to remove device owner
adb shell dpm remove-active-admin com.example.app/.AdminReceiver
Disables an active admin, the admin must have declared android:testOnly
in the application in its manifest. This will also remove device owner and profile owners
You can use DevicePolicyManager.clearDeviceOwnerApp() from your device owner app.
However note that this method has been deprecated in Android Oreo, you can still use it on Oreo devices but it might be removed in future Android versions.