Yes it's possible, but what you're asking is dangerous. The security problems surrounding this are going to bite you somewhere down the road. You can change the password field using a Field action, but you can not reset it from a Field action.
To randomize it you need to use a Code action with PHP method, construct the user object, and run setRandomPassword() function on it followed by a store. Example as follows.
Code:
$user = CBuser::getInstance( '[user_id]' );
$user->setRandomPassword();
$user->store();
Again, I really don't recommend doing this. Always use manual action for password reset (e.g. use Forgot Login).
nant
