Delete Override from Powershell

Hello,

we have scom 2012 sp1

basically i need to remove an override on the monitor.

how can i do that with powershell ?

note : i have only one override on the monitor, override is about enable value to true. i want to remove this override from powershell for only one monitor.

i try this link : http://scompro.wordpress.com/2011/09/14/opsmgr-bulk-overrides-deletion-thru-powershell/

but this link is for scom 2007. i changed the commands for scom 2012. but its not worked.