ingosch,
As an admin, I was able to login and submit a test event successfully, and then I was able to see my event in the Event List. My suggestion would be to reach out to the plugin developer and see if there’s some PHP code in the plugin that will allow you to disable it on a page-by-page basis. If so, then you should be able to perform a template override on the Community Submission form and add the code there.
We unfortunately can’t provide support for third-party plugins, but let me know what you discover after getting in touch with the other plugin’s developer. Thanks!
-Casey-