C Function in SAP "C_REMOVE"

Hello.

      Call 'C_REMOVE'

               ID     'DIR'                FIELD     'Directory Name '

               ID     'FILE'               FIELD     'File Name '      

               ID     'GROUP'         FIELD     'GRPNAS'

               ID     'ERRNO'         FIELD     l_errno

               ID     'ERRMSG'      FIELD     l_errmsg .

Can someone explain me the above line of  codes.

When I execute this lines , I get sy-subrc as 2 and l_errmsg as 'GROUP unknown', What does it mean?