..Simi,... if you have reached this stage, I believed to withdraw, that person just does not fulfill any of those PR fulfillment procedures,... but if you are asking if you can get back any processing fee (as a refund),... I believed it is not possible anymore.
As a further note, the next step after Medicals would be to pay the RPRF - so it's not necessary to pay this anymore, but as a matter of courtesy, do let the CHC know of the fact that there has been a change of mind,....