Hello MrVmware9423
Could you please elaborate your vCenter / ESX version ?
If you are currently using ESX 4.0 or 4.1, you can able to reset root passwrd via single user mode.
1. shutdown and reboot your ESX host
2. As soon as you see the GRUB boot screen, press space bar to stop the server from automatically booting into VMware ESX.
3.Use the arrow keys to select Service Console only (troubleshooting mode).
4.Press the a key to modify the kernel arguments (boot options).
5.On the line presented, type a space followed by the word single.
6.Press Enter. The server continues to boot into single-user mode.
7.When presented with a bash prompt such as sh-2.05b#, type the command passwd and press Enter.
8.Follow the prompts to set a new root user password.
9.When the password is changed successfully, reboot the host using the command reboot and allow VMware ESX to boot normally.
If you are using ESXi 3.5, ESXi 4.x and ESXi 5.0
Reinstalling the ESXi host is the only supported way to reset a password on ESXi. Any other method may lead to a host failure or an unsupported configuration due to the complex nature of the ESXi architecture
Hope it can help you. 
Thanks
Pramod