Can anyone shed any light on this? I feel like I have wasted the entire day today hunting and searching the internet for any scrap of information about how to do this. I have
Open your website's Handler Mappings in IIS Manager
Edit each handler you want to DELETE with, clicking Request Restrictions, choosing the Verbs tab, then add DELETE to the "One of the following" list or, if appropriate within your concerns, allow all verbs.
You might need to restart your website and/or recompile your code