Microsoft set up Windows 10 to default to using a Microsoft account with passwords for two reasons. You can set your copy of Windows 10 to not use the Microsoft password.

First reason is to enable you to integrate any Microsoft products with Windows 10, similar to what Google wants you to do when using Chrome connecting it to Gmail and Google Docs among others. Microsoft is wanting you to integrate with an email address at Microsoft, Office 365 and One Drive among others.

Second reason is for increased security. By requiring you to login your Microsoft account with a password then the machine (or copy of Windows) is only available to you. This is great for offices and on a laptop if you lost the laptop but if you are the only user in your location (for instance at my apartment only I am there normally) or if it is a computer you do not have private information on and is shared, the password is aggravating.

To get around the password requirement you will choose to use a local account which can be done when installing or after you have been using.

To change after you are using Windows 10, go to the Start menu (press Start button in lower left corner), Settings, Accounts, choose sign in with local Account. When it asks for password and to confirm leave them all blank. Now when you startup you will still click the signon button, but no password is requested.

Thanks Vivian for the question.