[Need Help] Remove remembered WiFi APs. - Android Q&A, Help & Troubleshooting

Hello,
I would like to clear all WiFi configurations from an app (programmatically) but not found any solution.
What I tried and it doesn't work.
WifiManager.removeNetwork
I try to use WifiManager.removeNetwork and found that it doesn't work on Android M+
then I try to set WIFI_DEVICE_OWNER_CONFIGS_LOCKDOWN to 0 with the command:
Code:
settings put global wifi_device_owner_configs_lockdown 0
and then try to WifiManager.removeNetwork again but it still doesn't work.
Remove configurations from /data/misc/wifi/wpa_supplicant.conf
Turn off WiFi then modify /data/misc/wifi/wpa_supplicant.conf and re-enable WiFi again. This method work properly on Galaxy S8 but doesn't work on Sony X Performance (my customer's main device)
WifiManager.factoryReset
This method used by Network Settings Reset (in Settings) but it is hidden and requires system privilege.
Use service call wifi <code>
To call WifiManager.factoryReset from a shell, you can use service call wifi <code> however the code depends on the Android version and the Manufacturer modifications. I found that code of factoryReset method is 63 on Android 7.0 and 7.1.1 but it doesn't work on my devices.
Device Owner
found that Device Owner App can make system setting modification, however to make an app as Device Owner requires to remove all account from device. (after make app as device owner, I can use WifiManager.removeNetwork to remove any Aps)
http://florent-dupont.blogspot.fr/2015/01/android-shell-command-dpm-device-policy.html
Can you please suggest me other solutions? (ROOT is acceptable but not a system app)
Thank you.

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The "service call wifi" is soo much depending on the Android version.
On Android 9 the call for resetting wifi to factory default is:
adb shell service call wifi 59 s16 wlan0
The proper call number can be found in the IWifiManager function. Like for Android 9:
android/android-9.0.0_r35 : android/net/wifi/IWifiManager.java
Count "case TRANSACTION_" from first to last. That gives you the call number. Pretty basic but it works!
To remove stored wifi networks:
cmd netpolicy list wifi-networks #to get list, index 0...
To remove network:
service call wifi 16 i32 1 #remove the second network in the list
(note 3rd doesn't become 2nd after this command!)
No root needed.
Remember this is for Android 9! Other versions may have other call numbers.
Edit: latest wifimanager here
Cheers