Microsoft officially provides an uninstall tool that can be downloaded and uninstalled. If you uninstall 32-bit and reinstall 64 bit, you must restart your computer after uninstalling.

Download the official Microsoft download tool: https://support.office.com/zh-cn/article/%E4%BB%8E -pc-%E5%8D%B8%E8%BD%BD-office-9dd49b83-264a-477a-8fcc-2fdf5dbf61d8? ui=zh-CN&rs=zh-CN&ad=CN