For creating a Kali Linux bootable USB, you need to download and install Win32 Disk Imager from the following source:
https://sourceforge.net/projects/win32diskimager/
Plug in your USB into Windows system. Note your drive letter associated with your USB such as “H:\”
Launch Win32 Disk Imager in your Windows and select the Kali Linux ISO Image from the folder icon on Win 32 Disk Imager. Double check the USB drive letter which is associated with your USB. Click the write button on Win 32 Disk Imager and confirm that you want to overwrite the contents on your USB.
Once the write is successful and Kali Linux bootable USB is successfully created, remove the USB from your Windows. Now by using this USB, you can boot Kali Linux