You can make a bonsai out of just about anything with a woody trunk (theoretically). I would let it grow for another couple of years, but I guess you could shorten it if you wanted, to encourage more and smaller branches, but I wouldn't do it below where there is any sign of buds or branching, only because I don't know if that tree will bud below that line (some do, some don't). If there is one (or more) 'lowest' branch, leave it to fatten the trunk over time (years), even if you eventually get rid of it as not fitting in with the eventual final design.

Thanks for the input.