I know Notepad++ is very complex. Is there any way to do this?

Yes, a script, e.g. python script, could do this BUT can we rely on your example data?
I mean, it is relatively easy to identify an url but getting the name part
of subdomain isn’t that easy.

So, does every subdomain follow your example?
This is hostname.sub.domain like www.translate.com?
Or could it be that you have also something like
http://x15w.sub.text.org/…
If the latter is the case, what should be used as the filename?
sub or text or sub.text or subtext or …

Cheers
Claudia