Hi,

It seems like you've covered most of the bases in terms of removing associations with the "x_group" model. However, if you're still encountering the error "This column contains module data and cannot be removed!", there might be some residual data or associations left.

Here are a few additional steps you can try:

1. Check if there are any records related to the "x_group" model in your database and delete them if possible.
2. Look for any customizations or code related to the "x_group" model in your custom modules or addons, and remove them if necessary.
3. Ensure that there are no remaining references to the "x_group" model in any other parts of your system, such as workflow rules, security settings, or other models.

If you try this steps, it may help you to resolve the issues

Hope it helps