This issue might also exist with other fields like the date field.

I am laughing at my use of "an URL". Wasn't intentional but it is the special language of the Composr catalogue field.

Wait really? I might have to check into that. Grammar rules would normally say it's "a URL" because you start with a Y sound, and Y is not a vowel. I'll have to check into that lol.

When anything is specified (upload, URL, etc), a tick box is present above the upload field for deleting the current file. If the box is ticked, then it will clear out the URL.

Modifying this behaviour will require more development time than what is worth on my end (JavaScript will need modifying and special considerations will need to be made considering the upload field could be on its own or in a field set). So I just simply edited the text of the tick box to be more concise and specify it also clears the URL if ticked.

I always assumed the deletion was on the upload field only, given the placement. The language change works :)

Yeah easy to assume that, and not easy for me to be able to separate it out unfortunately given the nature of form fields.