How do I uninstall the Relation module? I am trying to uninstall the modules that are part of the Relation module, after I tested it on my test site.

The Relation Endpoints Field module is not selectable because Drupal says the field implemented by that module is being used.



When I click on the "Field list" link, I get the following list of fields currently used.



None of the reported fields is implemented by that module; they are standard Drupal fields.

What should I do, in such cases? The content type that used that field has been already deleted.
This happened to me with a couple of modules last week; the solution was simply to run cron, allowing the fields marked for deletion to actually be deleted. After that I could uninstall the module in question without issue.