Kogavo, who was a silver medallist at the 2004 Olympics in Athens, refused to provide a test sample, a move deemed as a positive test result, the domestic MASZ news agency reported, and he was suspended for two years.
Fellow discus thrower Robert Fazekas was last week also kicked off the team for the London Games.
Fazekas, who was stripped of his 2004 Olympic title for doping, is facing a life ban for a second offence.
The athlete's lawyer said his client denied doping even though the thrower's B sample contained traces of a steroid.
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO Sports and on Facebook at AhramOnlineSports)
Short link: