New Rochelle High School principal Reginald Richardson on Tuesday night submitted his second resignation in less than three weeks, taking a secret buyout to leave for good, sources said.

Richardson abruptly lost a New York City Department of Education gig on July 21 after The Post inquired about his scandal-filled tenure, including a student’s stabbing death in January and an ongoing grade-fixing investigation.

A week after the DOE withdrew its job offer for Richardson to become a $160,000-a-year “quality review” director, he rescinded his resignation in New Rochelle, where he made $187,326 last year. Because the district had not yet accepted his resignation, it was moot.

On Tuesday night, New Rochelle board of ed president Jeffrey Hastie read aloud Richardson’s second resignation letter.

“After much soul searching, prayer and discussions with my family, I have decided to step down as principal,” the letter said. “I believe that the students and staff deserve to start the school year free of distractions and focused solely on learning.”

But district lawyers had negotiated a buyout deal, which was reached before the meeting, a board source said.

Officials refused to divulge the amount. “I can’t speak to personnel issues,” Hastie said.