Windows 10 allows you to configure any ONE local user account to automatically login to the system without typing a username and password. Obviously automatic login poses a security risk but if are ready to take that risk then the following procedure explains how to achieve that.
The procedure is different depending on whether your computer is on a workgroup of domain.
Auto login for computers on a work group
In case of computers on a work group you can easily configure automatic login from the Advanced User Accounts control panel - netplwiz
In the search box next to the Start button start typing netplwiz and click netplwiz command from the results.
Select the user account which you want to configure as auto login user
Uncheck the box Users must enter a username and password to use this computer
Click Apply You will be prompted to enter password for the selected user
Enter the password and click OK.
Next time you restart the computer the system will login automatically as this user without having to enter a password.
Auto login for computers on a domain
In case of computer on an Active Directory domain, you need to edit the Registry to setup auto login. A domain administrator can manually add these registry keys or if you need to repeat this procedure on a lot of computers you can also create a Group Policy Object to automatically add the registry keys.
To add the registry keys for auto login. Type regedit in the search box and select the registry editor.
Add/Modify the following key if they doesn't already exit
Restart the computer for the changes to take effect.