Hi,@Jaime Alonso
Thanks for posting your question in the Microsoft Q&A forum.
When you delete the old certificate, the old certificate reappears after ten minutes or so.
I have a couple of questions to confirm:
- Is your certificate expired? If it hasn't expired you don't need to delete it, just renew it.
- Is your Exchange a hybrid environment?
Here are my suggestions:
If your certificate has not expired, you just need to renew it.
Regarding renewing the certificate, you can refer to this URL: Renew the federation certificate: Exchange 2013 Help | Microsoft Learn
If the federation certificate has already expired, you need to remove all federated domains from the federation trust, and then remove and recreate the federation trust.
This is also detailed in this link: Renew the federation certificate: Exchange 2013 Help | Microsoft Learn
If my answer is helpful to you, please mark it as the answer so that other users can refer to it. Thank you for your support and understanding.