Python3.9.1 安装包下载地址 https://www.python.org/ftp/python/3.9.1/python-3.9.1-macosx10.9.pkg
安装直接双击安装包点同意继续直到完成安装，安装完成会有Python Launcher的小火箭和Python巨蟒的小图标出现在启动台。
彻底卸载Python3.9 1.删除应用 $ cd /Applications$ sudo rm -rf ‘Python 3.9’ 2.删除版本
/Library/Frameworks/Python.framework/Versions/3.9
$ cd /Library/Frameworks/Python.framework/Versions$ rm -rf 3.9 3.删除软链接
查询损坏的软链接
$ brew doctor
/usr/local/干净的胡萝卜/2to3
/usr/local/干净的胡萝卜/2to3-3.9
/usr/local/干净的胡萝卜/easy_install-3.9
/usr/local/干净的胡萝卜/idle3
/usr/local/干净的胡萝卜/idle3.9
/usr/local/干净的胡萝卜/pip3
/usr/local/干净的胡萝卜/pip3.9
/usr/local/干净的胡萝卜/pydoc3
/usr/local/干净的胡萝卜/pydoc3.9
/usr/local/干净的胡萝卜/python3
/usr/local/干净的胡萝卜/python3-config
/usr/local/干净的胡萝卜/python3.9
/usr/local/干净的胡萝卜/python3.9-config
$ brew cleanupPruned 13 symbolic links from /usr/local