Use a scraper to remove the loose paint coating from the wall first and clear the dust, dirt, sand, oil and mold with a wet rag completely.

请将准备要处理的墙面进行清洁，用刮刀刮除松脱漆膜并以湿抹布清除粉尘，特别是污垢、灰尘、砂土、油渍或发霉等处皆请先彻底清理。

youdao

I've put up with the neighbor who hired a couple of guys to remove paint from his house with an electric scraper and then disappeared for the weekend, the neighbor who uses a leaf blower at 10 at night, the neighbor who whacks weeds on Father's Day, the most immoral act known to man.

WSJ: Joe Queenan on the Sound of One Neighbor Misbehaving | Moving Targets