This one is pretty simple; using Proton Drive on a web browser, when I click on the thumbnail of a picture/video/file for preview, there is no way to be able to delete it. This is needed and IMO it is the right location to proceed for a deletion: when the file is being viewed. It is also helpful for files management and can help free spaces from your server, the planet, and our subscription.

Using FireFox 149.0 (64-bit)