How to uninstall a 3rd Party Extension
The process is the same as for uninstalling 3rd Party Components, Plugins and Modules.
They are all types of extension.
After you have uninstalled an extension
Check that no database tables have been left behind by the uninstallation script.
Also check that no directories and files have been left behind.
If database tables and files have been left behind then they pose a security risk.
How to uninstall an Extension