网上大多数方法在不具备用户权限获取的情况下都不能工作。

国外有人通过很简单的命令行就实现了：

Here’s how to remove Cygwin once and for all.

You will need

Cygwin cmd.exe 2 minutes
Run cmd, navigate to C:\ (or other disk, if you have installed it in different path).

This command takes ownership recursive of the folder, without asking anything:

takeown /r /d y /f cygwin
This command gives Full Access to Everyone recursively in the folder:

icacls cygwin /t /grant Everyone:F
And finally, the command which deletes it all and removes Cygwin:

rmdir /s /q cygwin