Here's how to delete a secret when using Security and Encryption for Coda:
You are working on a copy of the Security and Encryption for Coda – Secret template. ( Use the steps at Quick start to create a copy of this template)
You have editing access to the document.
You are the editor of the secret. (Here's how to Add or Update Roles.)
Navigate to the Secret Page. There, scroll down until you see the Secret Table.
At the Secret Table, find the secret you'd like to delete. To delete, click Manage Secret > Delete Secret.