Brinda Wilson-Demuth was scheduled to appear Tuesday.
However, coroner's counsel said Wilson-Demuth is ailing and the lawyers have decided they won't be calling her as a witness.
Other witnesses have testified the former warden of Grand Valley Institution in Kitchener, Ont., ordered records altered to avoid scrutiny from higher-ups.
Smith, 19, of Moncton, N.B., choked herself to death in her segregation cell in October 2007 as guards stood by.
Another senior prison manager, Joanna Pauline, is slated to testify Wednesday.