Unless you're actualy trying to spawn the fish (which won't be successful in a community setting anyway), don't worry about destroying the nest. He'll re-build it if he wants to and destroying it also reduces territoriality so may actualy be a good idea if he is becoming particularly aggressive. It's difficult for a bubblenest to become dislodged and float away without breaking up so I'd think your gourami abandoned his first nest a simply re-built one in the new position. That's not to say that the former isn't possible though.