How To Delete Email Search History On iPhone - Documents search

The search funtion on Mail app on iPhone allows to delete previous searches swiping left. But how do you remove previous 'Document' searche's which appear underneath?

Appears you cannot swipe to remove, hold to delete etc.

Restarting the iphone or closing the app and reopening does not clear the 'Document(s)' you have previously searched or opened after a search.