On Satellite v 6, unable to delete/remove Red Hat provided repositories, it says "You can not remove this repository because it is a Red Hat repository"

Issue

• Running out of space. I downloaded repositories that were not needed. Data is still on server after removing subscription from Satellite. Is there a way to clean old repository data or delete all the repository data off of the satellite server?

• There is no option to delete Red Hat repository using Satellite v 6 webui.

- Sync couple of repositories on Red Hat Satellite  v 6 server
- Go to Product -> Click on "Red Hat Enterprise Linux Server" -> Click on the repository to delete
- There is no option to remove repository, the question mark "?" sign says "You can not remove this repository because it is a Red Hat repository"

• Unable to remove repository using hammer command :

# hammer repository delete --id 6
[Foreman] username: admin
[Foreman] password for admin: 
Could not delete the Repository:
  Red Hat repositories cannot be manipulated.