Again, I don't know how your theme creates the slider - but I assume it may be via a custom post type in the theme's functions.php file. If there's a backend interface for organizing your slider (add slides, etc.) I assume there would be a field for selecting the URL you want the slide, when clicked, to go to. Put the hash tag (#) there.
Again, not knowing your particular theme and how it works means I can only explain ideas in general terms and you'll need to look into the code and figure out the best way of implementing them.
An even better solution (IMO) would be to add some jQuery function in your footer (make sure to use the jQuery no-conflict style of coding and to use WordPress' included jQuery library) to find the slider and basically remove the href attribute from all the slides inside it. Then no need to worry about hash tags. To do this, make a copy of the footer.php theme template file to use in your child theme and then in the bottom, just before the closing </body> tag, add this:
/*Replace .slider below with the id (#) or class (.) of the slider we want to affect with whatever html tags that follow to get down to the links*/
$('.slider li a').removeAttr('href');
So jQuery looks for anything with the class of "slider" followed by a
<li> (list-item) tag followed by an
<a>(anchor) tag. It then finds the 'href' attribute of the anchor tags and removes it - thus removing the hyperlink.
Anyway, this is another possible solution.
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