From the Settings:

Click the Start  button, then select Settings .

Select Update & Security.

Select Recovery.

Under Advanced startup, select Restart now.

After your PC restarts to the Choose an option screen, select Troubleshoot.

Select Advanced options.

Select Startup Settings.

Select Restart.

After your PC restarts, you’ll see a list of options. Select 4 or press F4 to start your PC in Safe Mode. Or if you’ll need to use the Internet, select 5 or press F5 for Safe Mode with Networking.

From the sign-in screen:

When you can’t open Settings to get into safe mode, restart your device from the Windows sign-in screen.  

On the Windows sign-in screen, press and hold the Shift key while you select the Power  > Restart.

After your PC restarts to the Choose an option screen, select Troubleshoot.

Select Advanced options.

Select Startup Settings.

Select Restart.

After your PC restarts, you’ll see a list of options. Select 4 or F4 to start your PC in safe mode. Or if you’ll need to use the Internet, select 5 or F5 for Safe Mode with Networking.

From a black or blank screen.

Before you enter safe mode, you need to enter the Windows Recovery Environment (winRE). To do this, you will repeatedly turn your device off, then on:

Hold down the power button for 10 seconds to turn off your device.

Press the power button again to turn on your device.

On the first sign that Windows has started (for example, some devices show the manufacturer’s logo when restarting) hold down the power button for 10 seconds to turn off your device.

Press the power button again to turn on your device.

When Windows restarts, hold down the power button for 10 seconds to turn off your device.

Press the power button again to turn on your device.

Allow your device to fully restart. You will enter winRE.

Now that you are in winRE, you will follow these steps to take you to safe mode:

On the Choose an option screen, select Troubleshoot.

Select Advanced options.

Select Startup Settings.

Select Restart.

After your device restarts, you’ll see a list of options. Select option 5 from the list or press F5 for Safe Mode with Networking.

How To Exit Safe Mode.

Press the Windows logo key + R.

Type msconfig in the Open box and then select OK.

Select the Boot tab.

Under Boot options, clear the Safe boot checkbox.