As mentioned in the above answer, DeviceAdmin API can help. If you are using an Android device, you might know about the Android Device Manager (the web-based version) which allows you to manage your device. Basically, you can track, locate, lock, and wipe your device, some of the basic features of an MDM solution. So, in coding (though I am not a coding expert), you need to get access to the Device Manager (I guess, using some listener codes, or notification access).
Apart from this, MDM allows creating policies and groups of users (which would be a part of the coding in the app itself), then pushing the command over the internet (or OTA) to the connected device.
MDM also allows managing Apps and Data on the device, for which, you need the app to get access to the internal as well as external device storage.
Hope this helps. Good luck creating your MDM software