I would like to understand the concept of List manager in Sitecore. Where is the data stored in Sql database of List manager. Showing list details:
Trying to understand where exactly the data is stored (Tables). And if we would like to delete the recipient count, then what would be the steps?
List Manager in Sitecore uses the "collection" database to store the values. It basically creates a contact in xDB whenever an email is added in the list manager, where the contact identifier will be "ListManager". You can directly query against your shared databases in SQL to get the contact id. If you will delete the contact from the List manager it will automatically update the recipient count once the XDB index will rebuild. you need to make sure your XDB index rebuild is working fine or you can try by manually run the XDB index rebuild - https://doc.sitecore.com/developers/91/sitecore-experience-platform/en/rebuild-the-xdb-index-in-solr.html
Your first question, the list data: List membership is stored in the xDB contact objects themselves, in the contact's ListSubscriptions facet.
Your second question, the recipient count in List Manager: At least in Sitecore 8 when I worked with it, the count in List Manager was stored separately and was not automatically synched if you programmatically added or removed contacts. You had to explicitly modify the count in List Manager; sorry, I no longer remember exactly how I did that.
