Yes, but do you think the masses are going to accept being sterilized? There would be an uproar of protest and the result would be war, the same way as if it were to just slaughter everyone.
No ones going to want to hear "your NOT allowed to have children", people wont just accept that. They'll fight it.
Itd be best off to release modified viruses that would, in some crazy way im sure is possible, only effect those people who had certain deffective disorders. Different viruses released for different disorders. Could start by spiking rec. drugs with them, that would spread it quickly.