The ear pads can be removed and washed.
To remove the ear pads, rotate them anti-clockwise to unlock (see image below).

The ear pads must be hand washed only, do not machine wash - the water temperature used should be in the range specified below. Then wait for the ear pads to fully dry.

Once fully dry, align the holes on the inside of the ear pads (highlighted with orange circles in the image below) with the clips on the headphones (located where the red arrows are pointing in the image below), now rotate the ear pad clockwise to lock the ear pads to the headphones again.