Since the basket is removable,you can separate it from magnet and leave both voice coil and magnet gap exposed.
Foam decomposes into a gooey mess but you have good probability to *carefully* remove it, both from coil surface using the universal rubber solvent: Toluene or Xylene.
Or the shop could carry a little can of "contact adhesive solvent/remover/cleaner" which is a mix of both.
I do NOT mean acetone or paint thinner, although "lighter fluid/naphta" may work ... sort of.
Wet goo ... let it soak ... wipe ... repeat and rinse ... literally.
Voice coil is relatively easy, gap is narrow so more complex but after 3 or 4 tries it should be squeaky clean.
Most speakers are practically unrepairable but here being able to separate them is a big bonus.