You can remove an entry for a document library (Web Storage System-based) from the configuration database. You would do this if, for example, you had an unrecoverable error on the document library server and you could not recover the document library.
The selected document library will be disconnected from the configuration database. If the document library is associated with a portal site, the Document Library area will be deleted from the home page of the portal site. The content source for the document library will be deleted.
After you disconnect a document library from the configuration database, the document library still exists on the document library server. If the document library is still functional, you can later connect it to a configuration database. For example, you might want to move a document library server from one server farm to another server farm.