So you've forgotten your administrator password to your Windows 10 PC and need to get in.
Warning: This method requires Physical access to the machine.
Boot Troubleshooting Mode
The easiest way to boot in Safe Mode with Command Prompt on Windows 10.
Boot as normal to the login screen.
Once you are at the Windows 10 sign-in screen, you should hold down the Shift key on your keyboard and not let it go. While holding down the Shift key, click on the Power button () and then click on Restart.
When Windows 10 starts, you will be at the Choose an Option screen
Click on the Troubleshoot button
Now click on the Advanced Options button
On the above screen, click on the Command Prompt
net user username password
net user adminstrator newpassword
The PC will reboot and login using the new credentials entered above