Change server name for SQLLocalDB instance Is there any way to change the instance name of LocalDB of SQL Server 2012 from (LocalDB)\xxxx to just xxxx?

I need it for an application that needs SQL Server DB instance name to be MSSQLDEFAULT.
No, there is no way to remove the (LocalDB)\ prefix from LocalDB instance names. LocalDB, which is a user-process, operates differently than "regular" SQL Server which normally operates as an NT service. So, at least in terms of client connectivity libraries / software goes, that (LocalDB)\ prefix is actually functional: it directs the client to another, LocalDB-specific, DLL for the connectivity. That LocalDB-specific DLL handles things such as looking for the existence of a currently running process for the instance being requested, and if not present, then it will actually start that instance and then connect to it (end result being that it just works).