Giardina was suspended from his position on Sept. 3 by Gen. Robert Kehler, who recommended to Defense Secretary Chuck Hagel that Giardina be relieved of his duties.
Obama acted on the recommendation because only the president can remove three- and four-star officers from their posts.
The Naval Criminal Investigative Service is continuing its investigation of Giardina that began after Iowa state police began an investigation in June into counterfeit gambling chips that had been introduced into a casino in Council Bluffs. State police said they contacted NCIS after Giardina became the focus of their investigation.
David Dales, a special agent in charge with the Iowa Division of Criminal Investigation, said the chips cost the casino "a significant monetary amount."
Giardina has been reassigned to a yet-to-be-determined position in the Navy.