ukinuti

1. (of a law, tax, institution) to abolish; to repeal; to revoke
   Vlada je ukinula taj porez prošle godine. — The government abolished that tax last year.
   Za građane Srbije ukinute su vize još 2009. — Visa requirements for Serbian citizens were lifted back in 2009.
2. (of a service, flight, line) to discontinue; to cancel
   Ukinuli su autobusku liniju do našeg sela. — They discontinued the bus line to our village.
   Aviokompanija je ukinula let za Beč. — The airline discontinued its service to Vienna.

The imperfective is ukidati; for calling off a one-time event (a concert, a meeting) otkazati is usually used.