Before beginning any repairs, turn off your headphones.

The earcup cushions of the Sony WH-1000XM3 are held in place by small plastic clips and it's the same removal procedure for both, the left and the right cushion.

In case you want to replace the battery you're required to remove the RIGHT earcup cushion.

Insert a spudger into the gap between the earcup cushion and the earcup frame.

A screwdriver or a flat pencil will also do the job but might scratch your headphone housing or damage the cushions.

Pry up the earcup cushion by tilting the spudger downwards to release the plastic clips.

Repeat the previous step around the perimeter of the earcup cushion to release the remaining clips.