Whenever I reboot my 2011 macbook air I get the login screen for my dads login information. He had previously used the computer and then gave it to me when he got a new one. After I enter the correct password for his login (which is different than my password for my login) it then logins to my desktop and account. However, when I do not completely reboot it, when it just goes to sleep, my login information comes up and i enter my password and then it goes to my desktop like normal. Is there a way to get rid of my dads old account? I think it may be responsible for why my battery dies so quickly when not charging. Any help would be greatly appreciated. Thank you.