MIAMI — On the night of his last game as an NBA head coach, Pat Riley heard the final buzzer, looked straight ahead and briskly walked away.

Deep down, he knew it was over.

“I didn’t have to look back,” Riley said. “I know that’s behind me.”

And now, after spending several days plotting the Miami Heat’s next course, Riley’s past becomes Erik Spoelstra’s future.

The Hall of Fame coach resigned yesterday, although he’ll remain team president. His first act as Miami’s former coach was to choose its new one, and hired Spoelstra, a 37-year-old who started in the Heat video room in 1995 and now becomes the NBA’s youngest coach.

Riley sees himself in Spoelstra.

Riley was 36 when he first became a head coach, and didn’t have any experience either. His first off-the-court job in the NBA was traveling secretary for the Los Angeles Lakers, handling boarding passes. Spoelstra also was at the bottom of the Heat totem pole when starting out, making videos for the team Christmas party, but Riley is convinced he’s ready for the top job.

“It’s very rare to have the opportunity to work for one organization for your entire career like I have,” said Spoelstra, who was told the job was his Friday. “It means it’s a special organization.”

Miami finished with the NBA’s poorest record (15-67), by far the worst of Riley’s career. As president, Riley will continue overseeing the plan to revamp a franchise just two years removed from a championship, after deciding he’d best benefit the franchise from the front office.

Last year, Riley said he was committed to coaching three more seasons. Yesterday, he admitted he never believed that to be true.

“I am definitely sure that I don’t want to do this anymore,” Riley said.

Riley’s future was among Miami’s many offseason issues. The Heat could have the no. 1 pick in the draft, are assured a top-four pick and are certain to make moves in an effort to revamp a roster plagued by injuries.

“Pat Riley has instilled in me values that enabled me to win a championship in just three seasons,” Heat guard Dwyane Wade said yesterday. “I’ve seen him do the necessary things to make us winners and I believe that with his focus on being president and his commitment to the team, we will once again become a contender.”