Exclude 1 blogpost from frontend?

Hi,

I tried to add to the “exclude” list one of my blog posts, but none of these variations work:

• https://testing.mysite.de/2019/08/one-blog-post/
• /2019/08/one-blog-post/

Isn’t it generally not possible to add a post from frontend to exclude list?
If it is possible, how has the URL to look like?

Thanks.