Use the following procedure to change the root password for a VMware appliance. This process uses single user mode so it allow you to change the root password if you have forgotten it!
Open the VM console and reboot the appliance
Select the line that starts with kernel and type e to edit the line
At the end of the line, press the spacebar and type init=/bin/sh
Press Enter to exit edit mode.
On the GRUB screen, type b to boot into single-user mode.
The virtual appliance boots in single-user mode.
To change the root user password, type passwd root and follow the on-screen prompts to enter a new password for the root user
To restart the virtual appliance, type reboot and press Enter.
When the virtual appliance restarts, you can log in using the new password.