Make sure that all your discount rules are disabled and are not in the process of deactivation ("pending deactivation" status).
Starting from January 2024, Shopify had improved the uninstallation process for apps. You can uninstall the app directly from the Shopify Admin. Go to Shopify Admin > Apps and uninstall the Bulk Discounts and Sales Manager.
Please read the instructions carefully before uninstalling the app.
Updated over a week ago