The Rockies designated Trejo for assignment Friday, Thomas Harding of MLB.com reports.
Trejo had seen semi-regular playing time in June while Brendan Rodgers was injured, but he went just 6-for-29 (.207) with four runs and an RBI since the start of the month. Trejo will hand over his spot on the 40-man and 26-man roster to Aaron Schunk, who'll provide some infield depth for the Rockies.