Microsoft Azure Cosmos DB now provides the ability to set the length of time in which a document lives in the database before being automatically purged. This length of time is referred to as the document's "time-to-live" (TTL) and is measured in seconds since the document was last modified. You can set this value at the collection level and override it on a per-document basis. If a time-to-live value is set, Azure Cosmos DB automatically removes documents that exist after that period of time.
For more information about time-to-live, see the Expire data in Azure Cosmos DB collections automatically with time to live article or the Azure Cosmos DB now supports time to live blog post.