After rooting and requesting superuser permission what do I need to do to enable/disable gps in my application?
You aren't supposed to to protect the privacy of the user. However it is possible by exploiting a bug. See this for how:
How can I enable or disable the GPS programmatically on Android?
Note that this may not work on all versions of Android - see
https://android.googlesource.com/platform/packages/apps/Settings/+/4b21f7cd9424eeb83838071a4419912ee5d5e41d
where they indicate it has been fixed but i'm not sure which versions have the fix (if any).