To request that an identity provider not be displayed by discovery services:

Log in to Federation Manager and click your IdP's entity ID in the list of Existing Identity Providers. 

Click "Entity Attributes" from the left navigation. The Entity Attributes section appears.

Check the box under the Assert Column for "Hide Form Discovery". 

IMPORTANT! Remember to navigate to "Review and Submit" to submit your entity for publication. Your changes won't be published to the InCommon metadata until you submit it for publication.

Further reading