Oh well...it seems this has been discussed before, but I didn't see the topic prior writing this one. My bad.
You don't have to apologize even if you had used the search feature you wouldn't have found that discussion
( something which needs work ). Hence why @TryNinja suggested to "google search".
I doubt it's a priority and from the quote above it doesn't look like it's a quick/easy fix to remove them, but them being there isn't really an issue.
From what I believe how this information is stored is in MySQL database, there are respective columns for each "Social network" and the values are stored in a row. If the columns are renamed to the other "Networks" that should do the trick but I guess it's not a priority for now...
I think it would be useful to restrict the link in the Website entry to a site owned and run by the member including the link.
The only "usefulness" I see is to prevent scams/phishing but then again its something which isn't moderated here, tbh I don't think we need it. What am interested in tho is what kind of click-rate do these website URLs get each month...
But how would you enforce that? And besides, I like using it for other stuff.
One of the ways that could be achieved could be via placing a small code in the header of the website you "own". Just like Google Adsense. You place a small code in your header which is then verified by google crawlers.