OG Extras did install 2 content types (group and post), which i can't disable anymore.

In the database > table node_type, there's a reference to OG extra's. So, this is the right issue-line ;-). I can remove the content types by hand from the database, but should i? And why can't i remove them through the UI? The delete link is gone (the edit not). In the database, the value custom is set to 0 (others are set to 1).

In the description on the project page, it says, that EVA adds the content types. But i don't have EVA installed.