Castillo was designated for assignment by the Phillies on Tuesday.
Castillo was claimed off waivers by Philly early last week but won't stick on the 40-man roster. The 26-year-old spent last season at the Triple-A level and had an .841 OPS in 124 contests. Kaleb Ort, who was claimed off waivers from the Marlins, will take Castillo's place on the Phillies' roster.