Here you find instructions on how to delete site columns from SharePoint’s content type hub.
- Open a site content type.
- On the top of the content type’s page, click on “Site Settings”:
- Under the “Web Designer Galleries” click on the “Site columns” link:
- Select the column that you want to delete from the content type hub by clicking on its name.
- On the bottom of the form, click on the “Delete” button.
- A site column that is being used in any content type will not be able to be deleted. To delete it, you first need to remove the column from all content types.