Starting at the ends of the speaker, prise the back case away from the main unit.

Work your way along the front of the case.

Once the front in freed, work you way along the edges, freeing the whole case.

There is A LOT of double sided tape between the outer and inner case. It requires a lot of work to remove it.

The case is one piece. Although it looks as if it splits at the rear, it is sealed together.