NBC "restructured" its programming departmen yesterday, and when the dust settled, there was no room left for Paul L. Klein, the brilliant and acerbic programmer who godfatered such acclaimed NBC productions as "Holocaust" and "Centennial."

Klein, NBC's top researcher on audience behavior from 1965 to 1970, was lured back to the network to take over programming in 1976. His reign was interrupted, however, when RCA Chairman Edgar Griffiths hired Fred Silverman away from ABC early last year and made him president and chief executive officer of NBC, the network that still ranks third in ratings.

Klein was trapped in Silverman's shadow and broadcast insiders were surpised the relationship lasted as long as it did. It ended officially yesterday.

However, NBC spokesman reshed to assert that Klein had not been "ousted" from the company and that NBC has enteed into "an exclusive production arrangement" wth him to supply programs to the network.

Silverman, asked if Klein's departure was simply an inevitability that finally had come to pass, said, "It isn't that cut-and-dried. Paul wanted to go into entertainment production. I don't think he enjoyed his job. He would rather do this." Silverman called the parting "very amicable."

Klein could not be reached for comment.

"I have enormous respect for Paul," Silverman said. "People will read all kinds of things into this. But this is something Paul wanted to do."

Klein had been occasionally and colorfully critical of Silverman's programs while Silverman ran ABC Entertainment. He once compared the ABC prime-time schedule to Top-40 radio and ridiculed the network for courting "kids and dummies" in its rise to the top. But an NBC executive said yesterday they became buddies when Silverman crossed over to NBC.

"I know that Freddie adores Paul," the executive said."He never stopped talking about him. Paul is a brilliant intellectual, a wonderful person. If he's free now to develop his own ideas, that's great, because that's what we need here more than anything in the world."

One of Klein's current pet projects was the ill-fated and costly "Supertrain," a series that limped out of the starting gate with a $12 million price tag but so-so ratings last month. It has now been yanked and will return later in the season, in a new and later time slot.

Silverman was asked it Klenhs departure had anything to do with the "Supertrain" pile-up. "No, it doesn't," Silverman said. "Paul is leaving because he really wants to. He came up with the idea for 'Supertrain' and I heartily endorsed it. Everyone was and is very enthusiastic about it. There's nothing wrong with the basic concept."

Dan Curtis, the producer of "Supertrain," was fired by NBC last week.

Under the restructuring announced yesterday, NBC's organization resembles that of front-runner ABC. Mike Weinblatt, president of NBC Entertainment, now has domain over all network TV operations. Reporting to him are John J. McMahon, senior vice president in Hollywood; Lee Currlin, promoted to vice president for program planning in New York; and Josh Kane, the programming vice president who began hs career at NBC as a page in 1965.

Klein's position, executive vice president, will be adbolished.

During his career at NBC, Klein was known not only for the creatin of programs but also for the coining of catch phrases that raced into vogue. He was the first to dub such Silverman ABC shows as "Charlie's Angles" Jiggle" shows, referring to the motion of female stars parading in front of the camea, and he invented the Least Objectionable Program (L.O.P.) theory of TV-watching, which maintins that people watch not the progrm they like the best but the one they dislike the least at any given hour.

Crusty, burly, and known around NBC as a "maverick" who never fit comfortably into bureaucratic niches, Klein had, networks insiders say, taken lately to roaming the halls and complaining that he had been reduced to the tole of a "clerk" by Silverman's assumption of programming decisions. Silverman now looks at all pliots and reads most scripts for proposed new series.

Indications that some sort of change was in the wind were apparent last week. A caller to Klein's New York office on Monday was told he had left for the coast, where he would spend the next two months. When the caller tried Klein's office at NBC in Burbank on Tuesday, a secretary said Klein had just left for New YORK. On Wednesday, Klein's secretary in New York said he had just left on "extended vacation."

"You know how networks are," said an NBC executive in Burbank. "You come in one day and your name off the parking space."