The incoming trusts page for the organization shows the accepted and pending incoming trusts:

Rejected trusts are not shown by default, but can be included by updating the search filters on the page.

To update an incoming trust request from a 3rd party organization, click on the Edit button next to the entry. This will display the incoming trust editor:

Using the editor, you can modify the status of the trust request, as well as setting an optional end date for any approval.

Important: Your externally-visible groups will not be visible to the requesting organization until you have approved the incoming trust request.

Click Save Changes to update the incoming trust:

Important: Please note that, if you reject an incoming trust request, it will be hidden from the incoming trusts list by default. Subsequent requests from the same 3rd party organization will not appear in the list. To change the status from rejected to approved, you must first show rejected trust requests, and then edit the request as described above.