1) Shut down the community that ends in /localsocial because it doesn't have any content, products or your billing info attached.
2) Free up the /localsocial URL in our system, then go change the /mylocalsocial domain to /localsocial.
Does that sound ok? It's not a true merge, but since you don't have posts in either community I think it'll work for what you need. Let me know and I'll make the changes right away. :)