I have deactivated a facebook account but it is still there?!?

[English Miss.]

I deactivated my sister's facebook account because she wanted to open another one using her own email address (the other one was with an email address she doesn't want to use anymore but wants her boyfriend to use it instead). I started another one up for her using the email she prefers but the deactivated one still seems to be there underneath the new one when I search her name. When you deactivate an account why doesn't it just disappear and go away forever?