Soon, an improved version with enhanced security of Security & Encryption for Confluence Cloud will be released. Please check out next steps for administrators at this page.
Overview
When you create a Secret macro, it is automatically available as an entity for the whole space.
The secret macros belong to the space not the individual page.
Deleting a secret from a page does not remove the secret form the space
to completely delete a secret from the space, you must delete the secret in the space
You must also be either the space administrator or the secret owner to perform secret deletion from a space.
Steps
In the Confluence left hand side bar menu
choose Secret List
select the title of the secret to be deleted
A page is displayed containing details of the secret.
choose Delete to send the secret to space trash
choose Delete to confirm the deletion
On the page with the secret, the Secret macro is rendered as locked and (Deleted).
Editing the page and removing the secret macro is recommended.
If you're a space administrator, you may restore or purge the space trash. This includes restoring deleted secrets from the space trash.