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