From Above. If the targeted leader has been democratically elected and enjoys popular support, the CIA has worked with elite groups, such as the military, to overthrow him (sometimes through assassination).  Among several examples is the first CIA-backed coup d'état, on March 30, 1949,  just 18 months after the agency's founding, when Syrian Army Colonel Husni al-Za'im overthrew the elected president, Shukri al-Quwatli. 

The CIA in 1954 toppled the elected President Jacobo Árbenz of Guatemala, who was replaced with a military dictator. In 1961, just three days before the inauguration of President John F. Kennedy, who favored his release, Congolese President Patrice Lumumba was assassinated with CIA assistance, bringing military strongman Mobutu Sese Seko to power.  In 1973, the US backed Chilean General Augusto Pinochet to overthrow and kill the democratically-elected, socialist President Salvador Allende, setting up a military dictatorship, one of many U.S.-installed military dictatorships of that era in Latin America under Operation Condor.