Merritt was optioned back to Triple-A Columbus on Tuesday, Zach Meisel of Cleveland.com reports.
Merritt, who was initially recalled last week, made his major league debut Monday, throwing 4.1 scoreless innings while allowing just one hit. The 24-year-old will head back to Columbus, where he holds a 2.94 ERA across 52 innings on the year, as the Indians bring up right-hander Shawn Armstrong to take his place in the bullpen.