When a Marketplace app creator deletes their public app, it's immediately removed from the public Marketplace and is no longer available to discover or install.
If the app has existing installations, it will enter a 30-day grace period, and its status changes to Scheduled deletion. During the grace period, organizations that have already installed the app will continue to have full access to it.
As the app creator, make sure you have the necessary arrangements in place to support these customers during the transition. If this is a paid app, contact your customers about canceling their subscriptions.
Public Marketplace apps with no existing installations do not enter a 30-day grace period when deleted.