Drops zero or more change points, which is done by dropping one change point at the
  time using *dropChangePoint()
  and recalculating the segment statistics at the end.
NOTE: This method only works if there is only one chromosome.
# S3 method for AbstractCBS
dropChangePoints(fit, idxs, update=TRUE, ...)Returns an AbstractCBS of the same class with
length(idxs) segments.
Henrik Bengtsson
For more information see AbstractCBS.