Uninstall[link] terminates an external program started by Install, and removes Mathematica definitions set up by it.
The argument of Uninstall is a LinkObject representing a MathLink link as returned by Install.
Uninstall calls Unset to remove definitions set up by Install.
See The Mathematica Book: Section 1.11.11 and Section 2.12.2.
See also: Install, LinkClose, Close.