The decision came after a defence ministry disciplinary procedure, sources said on Wednesday.
In the book, among other things, he says gays are not normal.
Vannacci also espouses the Great Replacement conspiracy theory about mainly Muslim migrants replacing ethnic Italians, says only white people can be Italian and lauds stand your ground self-defence laws.
On Monday, judicial sources said that Vannacci has been placed under investigation by Rome prosecutors on suspicion of instigating hate over the book after a number of associations complained about its content.
On Saturday, it emerged that Vannacci, a 55-year-old former paratrooper commander, has also been placed under investigation by the defence chiefs of staff for suspected fraud and embezzlement during his time as military attaché at the Italian embassy in Moscow.
ANSA
