Once you send the email, the mail server has sent the message and attachment over the network. You can delete your email and attachment and the recipient still receives the message and attachment.

I read somewhere that I can be deleted from the receiver email address... too bad if I can't cause I have sent an very important attach that it shouldn't be in that email.

The concept does exist, depending on account and software setup, but it is not a universal feature. For example, Gmail offers the ability to undo a sent email, but only up to 30 seconds.