GD > Post Title always links to the listing’s details page and has no option to turn the link off. You can remove the link with a short PHP snippet, or make it unclickable with CSS.

Remove the link with PHP

Add this with the Code Snippets plugin. It strips the link from every title output by GD > Post Title, including the titles in GD > Simple Archive Item cards, and leaves the plain text.

add_filter( 'geodir_widget_post_title_output', 'my_gd_unlink_post_title', 10, 2 );
function my_gd_unlink_post_title( $output, $title_tag ) {
	return preg_replace( '/<ab[^>]*>(.*?)</a>/s', '$1', $output );
}

Make it unclickable with CSS

If you only need the title not to respond to clicks, add this in Appearance > Customize > Additional CSS. The link is still in the page source, so search engines still see it.

.geodir-entry-title a {
	pointer-events: none;
	color: inherit;
}

Remove the link from the image too

In your Archive item template (GeoDirectory > Settings > General > Pages), set the Link to: option of GD > Post Images to None, which is link_to='' in the shortcode. If you use GD > Simple Archive Item, set its Image link option to No link.

Removing the links does not remove the details pages. They can still be reached from their URL and from search engines.