How easy is it? That depends on how comfortable you are with taking things apart and putting them back together. You have to take the motherboard up to get to the two screws holding the power flex down, and to do that you need to basically take out everything holding the board down.
Once you get the board up, you will notice one of the screws is located right behind the cables from the front display. At this point you can either gamble trying to get the screw out while the screen is still in, or take the screen out just in case you don't break the cable. To take the screen out you will need to remove the speaker, the screws at 4 corners, and loosen up the 6 screws securing the sides.
All in all the things you will need to be careful of are:
Not damaging the battery when you pry it out for the first time
Not damaging the wifi antenna when you pry it up
Not breaking the charging port cable when you separate it from the board
Not breaking the LCD cable/not breaking the screen when you try to remove the power flex screws
Not breaking the volume button and front camera flex when you lift/put down the board
Not breaking anything when you put the phone back together
Not misplacing/losing screws when you take it apart
If you're careful about it and put aside an hour or two you should get through it ok even if you're doing it for the first time.
As for the original question, once you take out the two screws at the bottom, you can push the backside up and then lift it out.
