Hide posts of a specific category from posts page

Hi Tom,

I tried to search but didn't find related topic in the forum.

Is there a way to exclude / hide posts in a specific category from the main posts page please?

E.g. My posts page is: mydomain.com/blog, a page that shows all posts of all categories. But I want to exclude posts under category 1 to NOT show in the page. BUT visitors can still access it from the right side bar where I have a widget to show all categories.

Thank you for your help.
Leon