DISCARD

        [CLEAN\]DISCARD [BufferName1 [BufferName2 ...]]]

    Discard  (i.e.  remove  from the memory and the list of known variables) the
    specified buffer(s).  Only the most  important  buffers  can  be  discarded.
    This may be needed in Memory hungry situations.

    DISCARD *
    will discard all image-like buffers:
      BEAM,  CCT,  CLEAN,  CONTINUUM,  DIRTY,  MASK,   PRIMARY,
      RESIDUAL,  SHORT,  SINGLEDISH,  SKY

    DISCARD UV*
    will discard all UV-like buffers
      UV,  UVCONT,   UVSELF,   UV_MODEL