Carefully remove the glue holding down the 6 wires to the back of the battery pack.

At this point, write down the colors and wiring order before desoldering.

Desolder the wires and lift away.

Flip the earpiece over the other side and carefully run the knife around the perimeter of the earpiece to free up any glue.

With the glue free, you can carefully push the battery pack assembly out of the earpiece.