There might be situations where there are specific users that you do not want to have the ability to reset their passwords. For example, you may not want employees with access to sensitive data to be able to reset their passwords using this Web Part.
To limit users from having this ability:
Please edit the web part and in the text box, you can choose to Exclude Users or Exclude AD Groups. If you are excluding user groups, please click that radio button. You may then enter the group names separated by semi-colons in the corresponding text box.