To unlock the uncensored version, choose where you want it, if for Steam or Itch. On Steam just buy the DLC, but if you want it here, click to "Download Now - Name your own price" then click on "Riding to Bounce City Win ver-0.8.2c uncensored.zip (721 MB) at $9.99 USD", buy it and download it.
You don't need to re-play the whole game, the save file is the same for both (if you are playing on the same PC you played it before).