When you set up Windows, you were required to create a user account. This account is an administrator account, which allows you to set up your computer and install any programs that you would like to use. Once you have finished setting up your computer, we recommend that you create a standard account and use it for your everyday computing. If you create new user accounts, you should also make them standard accounts. Using standard accounts will help keep your computer more secure.
The steps that you should follow will vary, depending on whether your computer is on a domain or a workgroup. To find out, see "To check if your computer is on a workgroup or domain" in How is a network at home different from one at work?
On the Users tab, under Users for this computer, click the user account name, and then click Properties.
Click the Group Membership tab, click the group you want the account to be in, and then click OK.
Click the account you want to change, and then click Change the account type.
Select the account type you want, and then click Change Account Type.
Windows requires at least one administrator account on a computer. If you have only one account on your computer, you can't change it to a standard account.