In this article you will find How to Reset Root Password for XenServer Host via xencenter or through ILO.
Note: The boot loader has been changed by Citrix in previous releases of XenServer.
1. First login into XenServer and to change the password you first need to go to that Server. After providing user Credentials go to Console tab > press enter to log in
2. Then type xsconsole and go to Authentication option and press Enter.
3. Go to Change Password option and press Enter ,it will prompt you a login window where you have to put old password.
4. After that provide new password and put the password again to confirm it and press Enter.
5. It will prompt you that your password has been changed and press OK.