Hi Andrew
Projects cannot be currently deleted but you can add new credentials to existing projects if you'd like to reuse the projects themselves.
Unfortunately, credentials that have been deleted cannot be retrieved. You will need to create new credentials.
Creating credentials with the User Management API requires System Admin permissions, no other permission incl Developer role are sufficient.
If you'd like, please send me a direct message with details on company name and what exactly you're seeing in the Console so I can try and help troubleshoot.
Best
Carmen