IDA Help: del_segm

Delete a segment
  ea      - any address in the segment
  flags   - combination of SEGMOD_... flags

success del_segm(long ea, long flags);

#define SEGMOD_KILL    0x0001 // disable addresses if segment gets shrinked or deleted
#define SEGMOD_KEEP    0x0002 // keep information (code & data, etc)
#define SEGMOD_SILENT  0x0004 // be silent
#define SEGMOD_KEEP0   0x0008 // flag for internal use, don't set
#define SEGMOD_KEEPSEL 0x0010 // do not try to delete unused selector
#define SEGMOD_NOMOVE  0x0020 // don't move info from the start of segment to the new start address
                              // (for set_segm_start())
#define SEGMOD_SPARSE  0x0040 // use sparse storage if extending the segment
                              // (for set_segm_start(), set_segm_end())