This answer works for my situation.
First you have give a repeat out put using ME9F.
Go to ME9F, Processing status 1 and select the one with green Tick mark and give repeat out put.
Now it means that the Purchase order it is ready for a new print out.
After doing the above you can unrelease the Purchase order using only ME28 only (not ME29N).
But i want to reset the release strategy in Tcode ME29N, is it possible.