1. Click Start and go to the Control Panel (in Windows 8, you need to press the Windows + X hotkey, then select the Control Panel menu item):

2. Select the Large icons view option:

3. Click User Accounts:

4. In the window that opens, select Manage User Accounts:

5. Click Add:

6. In the User name line, type Administrator, then click Next:

7. Select the Administrator access level, then click Next:

1. Click Start and open the Settings menu, then go to the Accounts menu:

2. Go to the Family & other people tab (in Windows 10 Professional, this tab is called Other users). Under Other people, select Add someone else to this PC:

3. In the next window, select I don’t have this person’s sign-in information:

4. Select Add a user without a Microsoft account and fill the fields below:

5. Enter a username, password, and password hint (if needed), then click Next:

6. Select the new Windows account and click Change account type:

7. In the next window, change Standard User to Administrator:

8. The new Windows account will now be available to select on the welcome screen:

For Windows 11, the process is slightly more complicated, since the Admin account is disabled by default. Please follow the advice on this page.