How to enable and disable the Windows Administrator account in windows 7, 8 and windows 10

Enable the Administrator account through the Local Policy Editor

Step1:
Start button and type Local Security Policy and press Enter on your keyboard.
Or
Hit windows key and letter r simultaneously and open run box

If prompted by a User Account Control screen, click on the Yes button.

Step 2:
When the Local Security Policy screen opens, expand the Security Settings folder,
then the Local Policies folder, and then click on the Security Options folder
so it is highlighted.
Scroll through the list and double-click on the policy named
Accounts: Administrator account status as shown in the image above.

Either select Enabled or Disabled depending whether or not you wish to enable or disable the built-in Administrator account. When done, click on the OK button to save your changes.