Use the CLEAR LINE command to remove line parameters (or reset the
 parameters to their default values) from the volatile database on
 the executor node.  For an X25 line, the default value depends on the
 NETWORK parameter in the permanent database.  Use the PURGE LINE
 command to remove line parameters from the permanent database on
 the executor node.

     CLEAR   KNOWN LINES     (parameters...)
             LINE line-id

 All underscores found in parameters must be replaced with spaces
 when parameters are used in NCP commands.