Just to be clear, I didn't came up with this idea. This is just a compilation of different ideas that I found on XDA on different thread to accomplish this.
Disclaimer: Do this at you own risk. I am not responsible for anything that happens to your device. I can only assure you this worked for me.
Use this steps to Sim unlock you G900P from Sprint running Lollipop 5.0
1. Downgrade your ROM from Lollipop 5.0 (OA6 ) to Kitkat 4.4.2 (NE5) using this link . Yes you can do this!!!
-Remember for this step you need Odin
2. Unlock you device by Installing and running SSU.apk using this thread
At this point your device should be unlocked. If you want to go back to Lollipop OA6 proceed to step 3.
3. Download the Lollipop 5.0 ROM OA6 from here and flash it using Odin by following the same steps on point 1.
That is all. I hope this helps you guys as much as it did to me.