This might be useful in a situation whereby Facebook un-publishes a Page you have linked to a Facebook group and you need to link the group to another Facebook page.
How To Get Started
Ensure you are an admin on the Facebook group and navigate to the group settings page as highlighted in the photo below by clicking on “more > edit group settings”
Scroll down to the “Linked Pages” section and click on the “edit linked page” button
Click the … button, click “unlink page” and click “done”.
Right here, you can also link the Facebook group to another Facebook business page.
Alternatively, you can go to your Facebook Page which you want to unlink, click the Groups tab in the left column, if it’s visible, click the down-facing arrow and select Unlink Group next to the group name.
No Group Tab in Facebook Page?
If the Group’s tab is not visible on your Facebook business page, go to your Page “settings”
Click “Templates and Tabs” on the menu on the left side. Select “Business” template, click “Add a Tab”.
From the pop-up window, click “Add Tab” for “Groups”.