There are a few helpful articles which may be useful for your particular Add-In:
http://www.mztools.com/articles/2006/mz2006018.aspx
First of all I tried this (which may work for you) How to: Deactivate and Remove an Add-In.
Note if you don't know the Namespace or ClassName of the addin, you can find it in the .addin file under FullClassName:
To remove an add-in from the integrated development environment (IDE)
- Delete the .addin XML registration file for the add-in that you want
to remove. The default location is ..\Users\username\ Documents\Visual
Studio 2010\Addins\
- At a Visual Studio command prompt, type devenv
/resetaddin Namespace.ClassName, where Namespace is the name of your
add-in project and Classname is its class name, for example, devenv
/resetaddin MyAddin1.Connect
For me this, although not my exact problem, lead to my resolution, which was simply to run Visual Studio as administrator. Doing this for just one version of Visual Studio solved my problem in that the error message no longer appeared (probably because it was then able to successfully rename as per the original error message).
devenv.exe /setup
? – Clemendevenv.exe /setup
do? – Incised