You are not required to use a Microsoft Account to use a Windows 10 computer, though it is recommended. When you are setting up a Windows 10 computer for the first time, there is an option for Use a local account instead or Skip this step when it asks to create a Microsoft account - you could choose not to use a Microsoft Account at this step. If the computer is already set up and you want to change away from using a Microsoft Account, here is information on how to switch to a local account instead:
http://www.microcenter.com/tech_center/article/9002/how_to_switch_to_a_local_account_login_in_windows_10