Creating a new master vault creates the KnowledgeVaultMaster.mdf and KnowledgeVaultMaster_log.ldf files to which the vault databases are attached.
You must detach all databases before creating the master vault. The master vault can only be created if KnowledgeVaultMaster.mdf and KnowledgeVaultMaster_log.ldf have been previously detached and removed from the C:\Program Files \Microsoft SQL Server\MSSQL.1\MSSQL\Data directory.