Hamilton-Goss said the charges in the letter had all been investigated by the board of directors or Fleischer's office and were found to be without merit.
But Rivera, a LULAC member and appointee from the city of Hawaiian Gardens, said he has found "sloppy management" since joining the board in June.
"When I started getting into management disbursements and financial affairs, I was flabbergasted," said Rivera, who is a program director at Jobs for Progress, which handles job training for several area cities.
No changes were made despite his protests to Fleischer, Rivera said.
Rivera also insisted that the board of directors had approved a budget. In addition, a quorum of directors had met several times in July and early August and no parent-approved budget had been presented to them, he said.