The Cubs designated DeWitt for assignment on May 6 in order to recall Travis Wood from Triple-A Iowa. Wood made one start in place of Matt Garza, who was suffering from the effects of a flu virus, and then was sent back down immediately after his outing.
DeWitt was not claimed by any other team after going through waivers. He could have declined his outright to Iowa and become a free agent, but he would have forfeited what was left of his $1.1 million deal for this season.
DeWitt is expected to report to Iowa on Friday.
It was the second time this year DeWitt could have opted out of his contract. He was taken off the 40-man roster in February when Adrian Cardenas was claimed off waivers from the Oakland Athletics. He elected to stay with the Cubs, though, and ended up making the big-league roster out of spring training.
In just 18 games this season, DeWitt batted .138 (4-for-29) with one RBI. DeWitt was acquired from the Los Angeles Dodgers at the 2010 trade deadline along with pitchers Kyle Smit and Brett Wallach for Ted Lilly and Ryan Theriot.