There is no way a user can delete his/her messages & notifications. It could be a long list of messages & notifications over the time and the user will not be able to make out which was already seen . Suggest a possibility of adding a "Delete all" function as mentioned in the screen shot below.
Thanks .
Due to the many requests in the past for additonal features and components we have decided to develope a premium version. Features like Hashtags, Videos, Polls, Events, Stories, Link Preview, etc included in it.
$199 (Life Time)