Save all your work.

In Start Windows logo Start button, select Settings Gear-shaped Settings icon > Accounts Contact icon > Your info.  

Select Sign in with a local account instead.

Type the user name, password, and password hint for your new account. The user name must be different than any others on the device. Note: If you’re using Windows 10, version 1803, you can add security questions—instead of a hint—to your local account to help you reset your password in case you forget it. Check your version of Windows 10

Select Next, then select Sign out and finish. Sign back in with your new local account.

If you didn’t add security questions to help you reset your password, it’s a good idea to create a password reset disk. If you don't do this and then forget your password, you won't be able to recover it.