Script For Deleting Computers in SCCM 2012

Dears,

I need script to remove all the remain computers in SCCM 2012, sometimes we are going to delete some computers in active directory but the computers still remain in SCCM 2012, so I need script or query to find all the computers which removed from active directory but still remain in SCCM 2012, because I don't want to go remove them manually one by one.'

Thanks..