In northwest Peking, a few Chinese here claim, is a building called "12,000 House." Its name denotes the number of unsold works by the late chairman Mao Tsetung that are being stored there while Mao's successors wrestle with his ghost.

Emboldened by an apparent new agreement on reshuffling the post-Mao leadership, the Communist Party Central Committee has removed huge slogans and portraits of Mao from the outside of two buildings on Tienanmen Square and issued a directive that "portraits, quotations and poems of chairman Mao in public places . . . be gradually reduced to an appropriate amount."

The directive, expected to be broadcast nationwide tonight and printed in all major newspapers Tuesday, also called for limits on memorial halls, biographies and special publicity for party leaders, living or dead. It left uncertain, however, how many of the millions of Mao portraits in homes and meeting halls across the country actually would come down.

Long lines of people still visit Mao's huge mausoleum that dominates the south end of Tienanmen Square. The directive ambiguously said existing memorial halls that "can be reconstructed should be transformed into social, economic, cultural and welfare institutions," but added that "there can be some commemorative establishments for Mao Tse-tung, Chou En-lai, Liu Shao-chi and some revolutionary martyrs."

There are people in the Chinese leadership who would like to pull the mausoleum down and consign all Mao's portraits to an attic, but they appear to appreciate the great political and emotional costs of dealing cavalierly with such an indelible image, so associated in the minds of the Chinese with the Communist Party. They are working very slowly, like demolition experts defusing an old, buried bomb.

According to one uncomfirmed, somewhat incredible, report circulating among Chinese here, students at a Peking college have been trying for weeks to tear down the Mao statue that dominates their campus.

"They dynamited it three times, but only succeeded in taking off part of a kneecap," said one person who heard the story third hand. True of not, the story nicley sums up the kind of success Mao's detractors are having in erasing his memory four years after his death.

The Politburo group led by Vice Chairman Deng Xiaoping has drastically overhauled Mao's educational and economic policies, returning to an emphasis on good grades and profits instead of political correctness. Each step has been justified, however, as something Mao would really have wanted if he were alive today.

The recent portrait removal brought an earlier statement from the official Foreign Ministry spokesman: "There have been too many portraits of chairman Mao hanging from public buildings. It is not significant politically.

We need some readjustment."

The cleansed walls of the Great Hall of the People will soon welcome delegates to China's National People's Congress, who are scheduled to confirm the latest advance of Deng's leadership group by elevating his protege, Zhao Ziyang, to the premiership. Deng and four other elderly vice premiers are scheduled to give up their government posts to younger members of their group, although they will continue to hold the all-important reins of party power. The others expected to give up vice premierships are Chen Yun, Xu Xingqian, Wang Zhen and Li Xiannian.

The current premier, Hua Guofeng, is scheduled to give up his post, but remain party chairman. Hua is not an old colleague of Deng, and it seemed that many in Deng's group would like to further diminish Hua's image as they diminish that of Mao, the man who made Hua chairman.

Mao's and Hua's portraits hang together in nearly every meeting room in the country, "but someday I'll bet they will all be replaced by something like that," said one longtime Peking resident, pointing to a traditional Chinese painting of orioles resting on bamboo shoots.

The chipping away at Mao has been going on for some time. Two years ago the People's Daily stopped putting all his quotes in boldface type and party leaders for months have spoken of his "mistakes." The underground rumor mills talk of investigations of his sex life and embarrassing revelations at an upcoming trial of his widow and others.

Younger Chinese, particularly those in Army units, have been asked to turn in whatever Mao buttons they still have from the era a decade ago when everyone had to wear medallions of the chairman. Many of them were made of titanium, valuable in aircraft manufacture, and some Chinese suggest that they are being melted down to help build the Chinese Air Force. sA foreign collector here now has 1,500 of the buttons, each one different, and expects that their increasing rarity will someday make him a rich man.

That may take years. For now, the Chinese leaders who drive into the central leadership compound, Zhongnanhai, still must pass a sign that says in huge characters: "Long live the invincible Mao Tse-tung thought."