This question includes a classic stereo type about Chinese people - that they are subservient and obedient to the whim and whimsy of government rule. People loved Mao - and they still revere him today. A simple diktat from the government would not cause everyone to instantaneous change their minds.
In the early 1980's, historian and scholars - with Deng's approval - changed the official interpretation of Mao's 2 big mistakes. The Great Leap Forward and the Cultural revolution came to be reported as what they were - horrible tragedies, and mistakes caused primarily by Mao. Is that de-Maoization? Or factual historical revision?
Between about 1800 and 1949, China, and the Chinese people had a ton of chronic problem. Mao and the CCP effectively ended the problems and restored a drug free economically growing stability. I'll list the problems that were in memory:
- Qing dynasty after 1800 was too corrupt to handle difficult problems
- The powerful English Navy supported drug dealers selling opium in China, and undermined much of Chinese society by forcing an open market on drugs, while undermining the Chinese economy through trade imbalance.
- European incursions to take colonial prize cities
- The Taiping revolt
- The first Japanese -Chinese war in 1895
- Russia territorial expansion in the 1860s
- Russian claims in historical Manchu provinces
- Multinational suppression of the boxer rebellion
- Many famines
- Instability after the fall of the Qing
- Drug dealing warlords controling large portions of Chinese territory
- The corrupt Foreign-sponsored GMD government in collusion with financeers
- Japanese invasion during WWII.
In 1980 (and today too), many people still remembered the misery of pre-1949; Mao and the CCP brought stability, security, and economic growth to China. The 120 year threat of foreign invasion was done, WWII was done, the civil was was done. Hospitals were being build, modernization was taken at full speed. This was a major accomplishment, all while maintaining territorial integrity.
The fact is, the people remember these accomplishments. The fact that you, and American propaganda, don't like him is an emphasis on the Great Leap forward and the Cultural revolution. Most conversations I have had with people who lived through these horrible events blamed Mao and the CCP directly for them. But they also maintained that things were still much better in 1965 than before 1949; and in the 1980s they continues to revere Mao.
I've spent a considerable amount of time in China. In the Town I live in (Population ~ 1 million) I have seen large organized protests. They are common even! How, do you think, are they dispersed? Easy - the mayor comes out after a couple days, asks what the problem is, the people tell him, and he makes a policy change to make them happy. For example, there was a neighborhood about to be eminent domained. Most people are happy to be eminent domained as they really cash out - but this neighbor hood wanted to be continue. The 30 people when to hang out in front of city hall for 5 days, then the mayor came out, and a few hours later the problem was solved.
Despite the stereotypes, Chinese people are not obedient drones who obey the government; they make decisions about their own future based on their observations. Mao was very popular in the 1980s, and it was not possible to remove him from public affection. Deng could fix the historical record about the GLF and CR, but did not convince everyone to dislike a popular figure.
Another point: Deng and the CCP required continued popularity to remain in power. Attempting to fully discredit Mao would have undermined their own authority.