Its too late now with out putting it thru a lot -
It is usually done when baby is 3 to 5 days old - the fact it wasn't done strongly suggests this is a back yard or uninformed breeder that thought it would be cute to have a litter of puppies - its why i get upset when someone decides to have puppies just to have "the experience " or to make money
OK i vented
now i'm done - but don't hurt that baby by doing it now - either love it with a long tail ( which can be cute ) or else find a different baby to love.