To clean out unwanted contact data from your collection databases, there are some referential integrity constraints that mean the deletions have to happen in a specific order. The following query will delete all contacts, facets, interactions, interaction facets, and contact identifiers from xDB.
delete FROM [xdb_collection].[ContactIdentifiers] delete FROM [xdb_collection].[ContactIdentifiersIndex] delete FROM [xdb_collection].[ContactFacets] delete FROM [xdb_collection].[InteractionFacets] delete FROM [xdb_collection].[Interactions] delete FROM [xdb_collection].[Contacts]
You will need to run this on both Collection shards.