Remove the black foam ring.

Try to do as much of this by hand as you can. You do not want to damage the ring as you will need it for re assembly.

Carefully run your knife between the ring and the outer metal edge.

Now using your hands and knife when needed remove the black ring from the speaker frame. Prying slowly. Take care not to tear it.

Once the ring is removed rub all of the old foam surround off and set aside for reassembly