its all held on many different sites that you must have visited and put the data on
Nonsense.
I've seen some of my details on Google crawled sites that I've never been to and are simply either information leaks by muppets or marketing lists that I've given no permission to.
Once its out there, its there for ever.
Nonsense.
Contact the underlying website owner (i.e. NOT Google), be polite, ask nicely. Once they have removed your details, you will find your details will disappear from Google upon their next crawl of the web.