in src/main/scala/org/apache/pekko/persistence/dynamodb/journal/DynamoDBJournal.scala [170:176]
private def purge(persistenceId: String): Future[Done] =
for {
highest <- readSequenceNr(persistenceId, highest = true)
_ <- deleteMessages(persistenceId, 0, highest)
_ <- removeLS(persistenceId)
_ <- removeHS(persistenceId)
} yield Done