Step 1: Kindly go to AD Mgmt --> User Modification --> Bulk User Modification --> Reset password.
Step 2: You can select the users whose passwords need to be reset through two options,
a. Import the list of users through a CSV file.
b. If all the users belong to an OU, you can choose that specific OU and click on search.
Step 3: Click on check all and then, apply.