拆除 (chāi chú) specifically means to demolish or tear down a structure or installation — like a building, billboard, or temporary facility. It is more focused on complete removal of a fixed object than 拆 (chāi), which is a general verb for taking apart anything (machines, letters, packages). 拆迁 (chāi qiān) adds the idea of relocating residents, so it's a broader urban-renewal term.