Could I not have to use a subdomain

[fzorb]

What if I wouldn't want to use mail.example.com, instead example.com? How can I make it so I can use that instead?

[ASKaraferias]

You don't want to do that, that's what the MX record is for. Even if your email is the mail.example.com subdomain, you can send and receive mails as user@example.com, i.e. you don't need to send/receive mails as user@mail.example.com.