Ran into this during an NCS install today, and just wanted to pass along the request. The request was to delete backup repositories, both from testing and from the original WCS to NCS migration.
The basic structure follows this:
This is case sensitive
Enter configuration commands, one per line. End with CNTL/Z.
test-NCS/testadmin(config)# no repository wcs-ftp-repo
While this is not in the configuration guide, Cisco did do a good job of making an intuitive CLI for the linux appliance.