To reset the root password on a Debian 10 system, edit the kernel command line at boot to add "init=/bin/bash" which will boot the system into single user mode. Once in single user mode, remount the root file system in read-write mode using "mount -o remount /" and then use the "passwd" command to set a new root password. Reboot to test the new password.

1. If you forgot your root user password on Debian 10, please go through the following steps to set a
new root password:
1. Start your Debian 10 machine and Press any key to stop the boot process.
2. Press “e” to edit the kernel command line parameters
3.
4. Use “down arrow” key for scrolling down. Go to the line that starts with the word “linux”
and use “right arrow” or press “End” button to go to the end of the line, and then add
“init=/bin/bash“ as follows-

2. 5. After you have added the entry, press “F10” to boot Debian 10.
6. Debian will now boot into single user mode, with the root filesystem mounted in “read-only
mode“.

3. 7. So, use below command to mount the root file system in “read-write mode“.
mount -o remount /
8. Finally, change the root user password using “passwd” command.
9. After rebooting, try the new root password using su command.