[{"_id":{"$oid":"60feedd4b3aefff2629b93b7"},"insertionDate":{"$date":"2021-07-26T18:15:57.564Z"},"sessionData":{"time":[1364,1374,1384],"yaw":[0.15,0.3,0.45],"pitch":[0.36,0.76,1.08],"roll":[-0.13,-0.25,-0.35],"heading":[-3.24,-3.25,-3.17],"ax":[-0.42,-0.41,-0.41],"ay":[-0.15,-0.13,-0.1],"az":[0.9,0.91,1],"gx":[0,0,0],"gy":[-0.01,0,-0.01],"gz":[0.02,0.02,0.02],"mx":[0.26,0.26,0.26],"my":[0.01,0.01,0.01],"mz":[-0.04,-0.04,-0.07]},"metaData":{"userId":123456,"gender":"M","ageGroup":"SENIOR","weightKg":70,"heightCm":175,"poolSizeM":50}},{"metaData":{"userId":123457,"gender":"M","ageGroup":"SENIOR","weightKg":70,"heightCm":175,"poolSizeM":50}}]

db.collection.update({"metaData.userId":123456},{"$unset":{"metaData":""}})