I found a step-by-step tutorial on how to take apart an iPhone 6 on iFixit. Here are the steps:
1. Power off your iPhone 6.
2. Remove the two screws next to the Lightning connector.
3. Place a suction cup on the screen, just above the home button.
4. Pull up on the suction cup to create a small gap between the display assembly and the rear case.
5. Insert the flat end of a spudger into the gap.
6. Gently twist the spudger to widen the gap between the display assembly and rear case.
7. Slide the spudger up the left side of the phone to break up the adhesive holding the display assembly in place.
8. Remove the spudger from the left side of the phone and insert it into the bottom right corner.
9. Slide the spudger up the right side to continue breaking up the adhesive.
10. Open the iPhone by swinging the display assembly up from the left side, like opening a book.
11. Remove five Phillips screws securing the battery connector bracket to your iPhone 6.
12. Disconnect the battery connector from its socket on your iPhone's logic board.
13. Use a plastic opening tool to gently pry up and disconnect both antenna connectors from their sockets on your iPhone's logic board.
14. Remove two Phillips screws securing the bracket over the rear-facing camera connector.
15. Use a plastic opening tool to disconnect both cables connecting the rear-facing camera to your iPhone's logic board.
16. Remove two Phillips screws securing the bracket over the front-facing camera and sensor cable connector.
17. Use a plastic opening tool to disconnect both cables connecting these components to your iPhone's logic board.
18. Remove three Phillips screws securing the bracket over the home button cable connector.
19. Use a plastic opening tool to disconnect this cable connector from your iPhone's logic board.
20. Remove two Phillips screws securing this bracket to your iPhone's logic board.
I hope that helps! Let me know if you have any other questions.
