A review you have switched off stays on your website until the connector is updated and a sync runs. Once that sync runs, the review is removed.
Why this happens. Automatic syncs run once a day on most sites. If the review still appears right after a sync, the page cache can hold the old copy for up to an hour.
What you can do. If a review needs to come off sooner, contact support and a manual sync can be run. To see the current version of the page, use a hard refresh or a cache-busted load.