You can disallow a category to be listed by search engines using an SEO plugin such as Rank Math. http://rankmath.com/
De-indexing a category can be easily done.
However for not letting your users click on the posts that can be a little more tricky if they are already on the category page.
One possibility is to use the CSS pointer-events. For example this would be your CSS:
.category-banana .post-content li a {
pointer-events: none;
}
Evidently we don’t have a link to your category in question therefore we cannot give the accurate CSS.