Incineration, though bone chunks will remain.
Hydrofluoric acid would be ineffective on said bones, thus either crushing until a fine powder like the rest of the corpse or fed to willing (and able) dogs to destroy the evidence.
Also, to dispose of the remaining ashes, mixing them with the normal feed of said dogs, to further render them untraceable.
Alternatively, the bogs here in Ireland are to be left alone (largely) and thus would not be dug up for peat. Thus, a suitably deep grave could be in order, were I pressed for time, though this would not be ideal, as the body would be preserved (see http://en.wikipedia.org/wiki/Bog_body ).