Hi Mohamad,
First, set the Read permission of the Email Template of the security role ofs all users to the User level.
The email templates in D365 are divided into organization templates and personal templates.
Administrators can see all the templates in Settings > Templates > Email Templates. Here it will show whether each template is organized or independent.
1. For OOTB templates, all users can access them, so the accessibility of OOTB email templates cannot be modified. We can only delete them so that users cannot access them.
2. For personal templates, we have set the Read permission of each user's email template to the user level, so personal templates can only be seen by their owners.
3. For new organization templates, all users can also access them.
If we want to make organizational templates only visible to the owner, then we need to convert them into personal templates.
Edit the organizational template, click Actions > Revert to Personal Template.
Then the email template can only be accessed by the owner.
