Find in this article all requirements and the step by step guide to reset your IPMI password 

Reset IPMI Password

Step 1: Access through SSH to you ESXi console (ESXCLI)

Step 2: Verify ADMIN user number

• Navigate to /bin directory
  
  

  cd /opt/syneto/bin

  or

  cd /opt/bin

• List ipmitool users

  ./ipmitool user list

It is very common to find ADMIN user as number 2 

Step 3: Set new password

• Now that the ADMIN user number is confirmed you can proceed to assign a new password to it
  
  

• /opt/syneto/bin/ ./ipmitool user set password 2 <new_password>

  Remember to replace the number accordingly to your situation

• Set your new password

  In this case we used password@123 as new sample password