I go about it by sending it off to someone who knows what they're doing
However if you are feeling confident about dismantling, cleaning and correctly reassembling your lens, properly collimated of course ... I understand that a mixture of distilled water, hydrogen peroxide and ammonia will remove fungus from lens elements ... though it is a pretty noxious mixture and when I tried it I felt sick for half a day ... remember if the infestation has been long standing, the fungal secretions may have etched the lens surface/coating, which means you won;t be able to remove the marks.
If the fungus tracks are small and not widespread, the chances are it won't be making much difference to your images, and the worst that can happen is a bit of loss of contrast.