We all had to face this issue some time. We can very easily reset/change the passwords for our Kali linux box. Just follow the below steps!
1. Boot up your Kali box; from the GRUB loader screen choose the “Advanced options for Kali GNU/Linux”
2. Press “e” to edit the boot commands before the booting process. You’ll get a window as below screenshot.
3. Edit the sequence as per below.
change “ro” to “rw” and add “init=/bin/bash” as per the below screenshot.
Press F10 to save and boot!
4. We’ll get a shell with root privileges, where we could execute commands to reset the password.
5. Just type passwd root hit enter. It will prompt you to enter the new password. Enter the password twice. Exit from the shell and reboot. You are all done!