You cannot uninstall plugins in JIRA 4.1 via the Universal Plugin Manager. See the Uninstalling Plugins in JIRA 4.1 section below for more information.
If you wish to remove a plugin from your application altogether, you can uninstall it via the Universal Plugin Manager (UPM). If you only want to temporarily remove it, you may wish to disable your plugin instead.
To uninstall a plugin from your application, navigate to the Plugins page and do the following:
Screenshot above: Uninstalling a plugin
Due to a bug in the Atlassian Plugin Framework, the Universal Plugin Manager cannot uninstall plugins in JIRA 4.1.x. You can find more information about the bug here:
If you need to uninstall a plugin, please follow the JIRA 4.1 documentation for uninstalling a plugin.
This bug has already been fixed in Atlassian Plugin Framework 2.5, which will be present in JIRA 4.2 and later. A newer version of the Universal Plugin Manager will reinstate the ability to uninstall plugins in JIRA.