Deleting a project link stops the two projects from sharing information.
If you have set up multiple project links to the same application, for example you have linked a Confluence space to multiple JIRA projects, deleting the primary link will mean that another of the links will be made the primary link.
To delete a project link:
Choose Application Links.
Choose the Delete link next to the link that you want to delete.
A confirmation screen will appear. Click the Confirm button to delete the link.
Screenshot above: Confirming the deletion of a project link