No idea how to remove.
However you could wash/flood it with distilled water. Note the distilled.
Distilled water is heavily use in electronic component manufacturing. Circuit boards, etc.
Being distilled it does not create/cause corrosion etc. side effects.
NOTE!
1) Disconnect the vehicle battery and allow to stand for 15 minutes before washing/flushing.
2) Leave for say 12+ to 24+ hours before reconnecting the battery