Fr Delta described to the inquiry how he had been struggling for some time with spiritual problems arising from his behaviour with boys in January 1966.
He said he realised the important thing was to remove himself from the boarding school in question, St Peter's.
The priest approached Bishop Herlihy and asked to be removed from his teaching post. He said he was not asked why and was appointed to a half-parish in the diocese.
He was later accused by Bill and Terry of sexual abuse. But both were unwilling to pursue a case against him. The inquiry says this highlights the need for a willing complainant.
The report said it was satisfied gardaí made sufficient efforts to procure the co-operation of the complainant, but was concerned at their failure to acknowledge notification of the allegation by the diocese.
The inquiry finds that Bishop Herlihy was aware that Fr Delta had abused boys in the school in the mid-1960s. It criticises the decision to appoint him to a half-parish, where he would receive no supervision or monitoring. The inquiry adds that had help been available to Fr Delta at the time of his actions, further abuse might have been avoided.