If you have Policy Manager you can use that to manage MAC Locking. To do so, select the device in the tree on the left side of the screen in Policy Manager then the MAC Locking tab on the right screen. Push the retrieve button and it will pull in all the mac locked addresses along with their locking cause. You may then highlight the entries you want cleared then push the Remove button. Take note that if you don't change the port or device settings, it may come right back again.
I'm pretty sure that you'd find the right entry in the MAClocking MIB....
Could you please post a example of the switch locking MAC configuration so I'd see how you've setup the function.... i.e. static/firstarrivel, aging....