How can I uninstall an Add-on? I asked a question yesterday about how to bring filled polylines in from AutoCAD without them coming in as joined filled shapes.  I was directed to a download site to get a new dxf importer.  I installed it as directed but now I have two dxf converters installed in Blender and they conflict so that I can't bring dxf files in at all.  How can I uninstall the old one?

I suppose I could uninstall Blender and then reinstall it, but then I would have the same question.  Can I bring in polylines from AutoCAD without them linking to each other and creating a maze of linked filled shapes?
You need to delete the .py file. To do this on windows, go to C:\Program Files\Blender Foundation\Blender\[version]\scripts, and find the scripts location. Then delete the files.

Here in the screenshot of the user preferences (Which can be accessed via Ctrl-Alt-U>Scripts) you can see the location of the script files that need to be removed.