just make a new account and delete your dad's account
it's easy just remember to make a administrator account
read the foll to help you
To Create a New User Account
1. Click Create a new account in the Pick a task list box.
2. Type the name that you want to use for the account, and then click Next.
3. Select the desired account type, and then click Create Account.
To Make Changes to an Account
1. Click Change an account in the Pick a task list box.
2. Click the account that you want to change.
3. Select the item that you would like to change:• Click Change the name to change the name that appears on the Welcome screen for the account.
• Click Change the picture to change the picture that is used to represent the user account. You can use any image file on the computer for the user's picture.
• Click Change the account type to change the account type to increase or decrease the user's rights on the computer.
• Click Create/change the password to create or change the password for the user and create or change the password hint.
• Click Delete the account to delete the user account from the computer. When you delete the account, you are given the option to save the user's files on the computer.
Note: You can not delete the account for a user that is currently logged on to the computer.
To change your computer's name in Windows XP, follow the steps below:
Log into your computer with administrative rights.
Note: At Indiana University, the IT Security Office (ITSO) recommends that you normally run your Windows computer as a member of the Users Group, not as an administrator or a member of the Power Users Group. For more information, see In Windows 2000 and later, why should I avoid running my computer as an administrator or Power User? For tasks requiring administrative access, you can gain it quickly using the Windows Secondary Logon service. For more information, see What is the principle of least privilege?
From the Start menu, open the Control Panel, and then double-click the System icon. Alternatively, right-click the My Computer icon, and from the menu that appears, select Properties.
You will see the System Properties window. At the top of the window, click the Computer Name tab.
Click Change... . You will see your computer's name listed.
In the space marked "Computer Name:", delete what is there and type the name you want to give your computer (at IU, this is usually your Network ID username). Click OK.