Database
db={"profile":[{"_id":1,"interests":["sports","sing","read"],"interest":[ObjectId("5a934e000102030405000001"),ObjectId("5a934e000102030405000002"),ObjectId("5a934e000102030405000004")]},{"_id":2,"interests":["tracking","travel"],"interest":[ObjectId("5a934e000102030405000000"),ObjectId("5a934e000102030405000003")]}],"interests":[{"_id":ObjectId("5a934e000102030405000000"),"name":"travel"},{"_id":ObjectId("5a934e000102030405000001"),"name":"sports"},{"_id":ObjectId("5a934e000102030405000002"),"name":"read"},{"_id":ObjectId("5a934e000102030405000003"),"name":"tracking"},{"_id":ObjectId("5a934e000102030405000004"),"name":"sing"}]}
Query
db.profile.update({interests:{$exists:true}},{$unset:{interests:1}},{multi:true})