1. Shutdown and Reboot your VMware ESX Server
If you don’t know the VMware ESX Server root password, you don’t know any passwords for root-equivalent accounts, and your virtual center server also does not have it cached, the only way to change the root user password is to first shutdown / power off your VMware ESX Server.
2. Press “a” to modify the kernel arguments
As soon as you see the GRUB boot screen, press “a” to modify the kernel arguments, like this:
3. Enter single user mode
At the end of the kernel arguments command line, type “single” and press Enter, like this:
4. Change the root password
Now, change the root password using the passwd command, like this: