Reviews in GeoDirectory are WordPress comments with a star rating, and you turn them off per post type:

1. Go to Places > Settings > General (or the settings of your other post types).
2. Tick Disable comments.
3. Save.

That closes comments and reviews on every listing of that post type, and the rating stars and review count from the GD > Post Rating element no longer show.

The other review settings

On the same page:

• Disable ratings removes the stars but keeps comments. Its description says “Disable review stars without disabling comments”, so if this is the only box you tick, the comment count (for example “No Comments”) still shows.
• Single review lets each user leave only one review per listing.
• Disable favorites removes the favorite button, if you want that gone too.

If a Reviews tab still shows on the listing page, remove it at Places > Settings > Tabs.

Use these GeoDirectory settings rather than Settings > Discussion in WordPress. The WordPress option to allow comments on new posts only sets the default for posts created after you change it.

To close comments on one listing only, see How to disable comments on a listing.