Using a pair of tweezers, poke the square plastic piece between each of the buttons that connect them together. Each button has a plastic piece between their gaps.

While poking the square piece in, simultaneously push it upward to release it.

After releasing the first one, use the pair of tweezers, and do the same with the second one. This should free all buttons from the device.

Once the buttons are free, use the set of tweezers to grab the buttons and pull them out.