As a best practice we should remove public folder store from exchange front end server.
I have tried the arcticle on Microsft site that states that just right click the store—> click move all replicas–>select the server
& wait till public folders instance is empty & then remove the store.
After doing this the goal was not achieved & still I got no success.
Then an idea arrived in my mind why not to remove the record via adisedit…
eureka…I have succeeded by opening adsiedit.msc & browsing to exchange front end server —>removing the entry of public folder store.
So good luck if you are able to do via Microsoft way other wise use adsiedit.msc to remove it.. (make sure store doesnt have any data in it)