Change URL Login From /wp-login.php to login.abc.com

I’m sure I’ll regret asking: why do you want to do that?

Is login.abc.com some single-sign on site URL or do you want to do this for some other reason?

You can use iThemes Security plugin to change;

https://Www.abc.com/wp-login.php
to
https://Www.abc.com/Login (or what you want)

And

Login.abc.com is a subdomain

You can cerate a redirect html index in that subdomain(Login.abc.com) to go https://www.abc.com/Login

This is my amateur solution for you :]

Thx.