How to unload/remove unused *.sys driver from memory ?

[Camille Petersen]

A certain application loads a *.sys into the memory. It works fine.
However when I exit this application and re-start it again later again resp.
another version of this application an error occurs because of incompatible driver versions.
The driver can be seen with tools like DriverView.

I don't want to start a discussion on how bad this is programmed.

I just would like to know how to unload resp. remove an *.sys driver from memory (without
rebooting).

Camille