When you set up Windows, you were required to create a user account. This account is an administrator account that allows you to set up your computer and install any programs that you'd like to use. Once you finish 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 What is the difference between a domain, a workgroup, and a homegroup?
On the Users tab, under Users for this computer, click the user account name, and then click Properties.
On the Group Membership tab, click the group you want the account to be in, click OK, and then click OK again.
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.