You can install a newer version of LimeWire without uninstalling previous versions. This allows you to revert to previous versions if you don't like the changes in the new version or if the new version is unstable on your set-up.

But the old version is still there. If you cannot uninstall using the Add/Remove software option from control panel (Microsoft doesn't support this anymore because they could never get it to work reliably) - then you can find the files using windows explorer or similar and delete them from there. The usual install path is:

Program Files/LimeWire

All the versions and your shared files are under here by default so don't just delete the whole thing.

Mark