How Can I Remove an App Inbox Message?
By default, you can't remove a message without an expiration set once it's been sent to the app inbox. It is also impossible to modify the expiration of an app inbox that has already been sent.
An alternative option to removing app inbox messages is to use expiration.
How To Remove Expired Messages
The Mobile SDK doesn't check the expiration time for app inbox messages; Bloomreach filters these messages in the background. Therefore, to remove expired messages, you can use anonymization, which forces the dropping of cached expired messages so they will no longer be shown to customers.