My guess is that you uninstalled some of the individual plugins or the module and then tried to uninstall the package. If you did that, then the package won't be able to find the individual bits it's trying to uninstall.
I'd recommend re-installing the package, so that everything is replaced properly.. then, uninstall the Sendy package.
Hopefully that gets you going, but if not, let us know.
Thanks for your reply. I got this error message while trying to uninstall the package. After that, I uninstalled the individual plugins and module and retried with the same result, as one would expect. I've now reinstalled the package, and the same error occcurs when trying to uninstall it. All plugins and modules are installed.
Sorry for the delay in response. It looks like the package name in the original package xml file was incorrect, which is what is causing this problem.
To fix the uninstall, you'll need to do the following:
1. In your database #__extensions table, please find the row for the Sendy package and change the 'element' field to "pkg_sendy"
2. In administrator/manifests/packages/pkg_sendy.xml file, please replace
<packagename>Sendy Integration for Joomla</packagename>
3. Go back into the Extension Manager (possibly need to Refresh Cache for the sendy package)
4. Select Sendy package.
5. Click Uninstall
This should fix your problem. Sorry for the inconvenience and let us know if you still have problems after performing the above steps.