In order to make the Galaxy S6 / Galaxy S6 Edge premium build design a full-metal unibody sleek design, Samsung had to sacrifice the user-replaceable battery and the micro SD slot as well, the un-removable battery is annoying to most of the users, So we decided to publish Samsung's official Instructions on How to safely remove the Galaxy S6 Battery. The instructions are on the PDF file on the source link below.
The step-by-step instruction is somewhat vague in the beginning with step 2 being simply Remove the back cover. Experience from previous smartphones with similar construction points to a heated-air gun to melt the double-sided adhesive and guitar picks to separate the panel, all accompanied by an appropriate amount of patience.
Once that's out of the way, no less than 13 screws need to be undone to remove a circuit board allowing access to the battery. To sum it all up, the possibility is there, but you wouldn't want to do it yourself, and certainly not on a daily basis.