how do I delete files from the files app - again?

This question has been posed a couple times. I have some files that were put into my apple files (into a folder that can be seen under 'On My Phone" under the Browse icon) and when I hold the file, I see the standard list of things you can do (Get Info, Rename, Compress, Duplicate...etc) but there is no "Delete" or Remove item.

I have seen responses to this question where they tell the individual to go to the App which put them there in the first place and delete them from there. I put the ones I am trying to delete in place by sending them to myself in a Gmail account - using that up arrow symbol to send them to Files. So I don't know if there is some association with Gmail that would elucidate how to delete them - but anyone who could help would be greatly appreciated !