How to disable e-mail field (required) for registration of users

Hey. I have 2 questions.

If I am in the wrong subforum, so please notify me and move it to the right forum. Thank you.

So, 1.) Where does Wordpress ( and the other CMS) save the files? The static websites? Is there a folder, where the - for example - aboutus.php,
index.php, ...php, and so on is saved? Or are the whole static sits really saved in the database? I am asking this question, becaus I wanted to know if it is really not possible to edit some .php pages manually... add some code manually and delete some manually..

and, 2.) I know many Websites, made with WORDPRESS and some made with DRUPAL, where - for example - the "e-mail" field is not required and is not shown while new user sign up/registraton...How is this madeable?

---> BECAUSE: I am creating a website for anonym studies. So there users should only need a username and password for sign in. To be very discrete.

I have seen wordpress and some other cms' sites, where this is not required ( or not shown). Does anyone know, How I could realize that? And if it is not possible doing anything complicated... yeah, whant doing..? - is it possible, that the E-mAIL field is hidden and every user gets an e-mail-adress like " Username @ domainofthesite.com" ? If yes, how can I hide the required email field and manage that everyone gets an email adress like above? .........


Please help me!! Thats really important, when creating a website for victims of
domestic abuse /violence, because nobody will enter their real email adress. If it is not needed, then I don't want it while signing up!


Long post, sorry. But pls pls help me!!!!
Thank you all!