How can I disable the Out of the box email - Milestone notifications?

Summary:

Hi,

I have enable the milestone notifications for HR helpdesk service request. I am additionally receiving the 'OUT OF THE BOX EMAIL - First Response Metric expired'

mail notification. Can I know how to disable the Out box email.

Please find the attachment of the Out of the box email screenshot.

Content (required):

OUT OF THE BOX EMAIL - First Response Metric expired

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):