Force a password reset for G Suite (former Google Apps) users in a group. Also skip (some) user(s) if you want to.

google-apps-script-reset-password.js

/**
 * Periodic reset all user password in a Google Apps (G Suite) group.
 * Optional: skip users based on emailaddress
 *
 * -- You need Google Apps (G Suite) admin rights to run this script. --
 * -- Use Google Apps script triggers to force resets periodically. --
 *
 * @author: Denver Sessink <https://twitter.com/webvakker>
 */
function periodicPasswordReset() {
  
  try {
    
    var SKIP_USERS = ['boss@example.com'];
    var GROUP_EMAIL = "group@example.com";
    
    // Get group by GROUP_EMAIL and fetch all users of this group
    var group = GroupsApp.getGroupByEmail(GROUP_EMAIL);
    var users = group.getUsers();
    
    for (var i = 0; i < users.length; i++) {
      var user = users[i];
      var userEmail = user.getEmail();
            
      if ( SKIP_USERS.indexOf(userEmail) > -1 ) {
        // Skip this user
        Logger.log("Skipping: " + userEmail);
        continue;
      }
      
      Logger.log("Forcing password reset for: " + userEmail);
      
      // Change password at next login -> true and save!
      var userObject = AdminDirectory.Users.get(userEmail);
      userObject.changePasswordAtNextLogin = true;

      AdminDirectory.Users.update(userObject, userEmail);
    }
    
    GmailApp.sendEmail(
      Session.getEffectiveUser().getEmail(), 
      'Log for User Pass Change Script: Successful', 
      Logger.getLog()
    );  
    
  } catch(e) {

    Logger.log('--------------------------------------------------------');
    Logger.log('Error occured: '+e.message);
    
    // Send an email to yourself with logs
    GmailApp.sendEmail(Session.getEffectiveUser().getEmail(), 'Log for User Pass Change Script : Error occured', Logger.getLog());
    
  }
  
}

Wed Feb 07 14:33:52 EST 2018 INFO: Error occured: "AdminDirectory" is not defined.

@halburgiss, you need to activate Google Directory Services

Resources -> Advanced

This is a quickly thrown variation that would force-reset password for all users in the domain.

function forcePasswordResetForAllUSers() {
  try {
    
    var SKIP_USERS = ['some.user@example.com',
                      'john.doe@example.com',
                     ];

    var options = {
      domain: 'yourdomain.com',
      maxResults: 500, // TO-DO: implement pagination
      orderBy: "email"
    }

    var response = AdminDirectory.Users.list(options);
    
    response.users.forEach(function(user) {
      var userEmail = user.primaryEmail;
      
      if ( SKIP_USERS.indexOf(userEmail) > -1 ) {
        // Skip this user
        Logger.log("Skipping: " + userEmail);
        return;
      }
      
      Logger.log("Forcing password reset for: " + userEmail);
            
      // UNCOMMENT THE FOLLOWING THREE CODE LINES IF YOU WANT TO ***REALLY*** FORCE-RESET ALL PASSWORDS.
      // Note: running the script with the following lines still commented is akin to a DRY-RUN (you will still get an email as if the script was run for real, but nothing would have been changed)
      
      // Change password at next login -> true and save!
//    var userObject = AdminDirectory.Users.get(userEmail);      
//    userObject.changePasswordAtNextLogin = true;
//    AdminDirectory.Users.update(userObject, userEmail);      
    });      
    
    GmailApp.sendEmail(
      Session.getEffectiveUser().getEmail(), 
      'Log for User Pass Change Script: Successful', 
      Logger.getLog()
    );  
    
  } catch(e) {

    Logger.log('--------------------------------------------------------');
    Logger.log('Error occured: '+e.message);
    
    // Send an email to yourself with logs
    GmailApp.sendEmail(Session.getEffectiveUser().getEmail(), 'Log for User Pass Change Script : Error occured', Logger.getLog());
    
  }  
}