python - How to delete ndb ComputedProperty -

i can't del on computedproperty.

if remove property in model, then, when result can see last value.

dbexamcorrection(key=key('dbexamcorrection', 4519216128458752), aid=6744627663077376, c=0, ca=0, correct=5, created=datetime.datetime(2016, 1, 26, 11, 40, 10, 35968), dm=0, feedback=none, ga=0, gv=0, ic=0, l=0, o=0, p=0, percent1=83.33333333333333, percent2=0.0, percent3=0.0, percent=none, questions=6, score=none, sum2=0l, sum=0l, tid=0, updated=datetime.datetime(2016, 1, 27, 7, 43, 47, 951561)) 

but if access value, raises:

'dbexamcorrection' object has no attribute 'percent1' 

i don't want store obsolete information in model.

thanks in advance.

one approach outlined here - migrating data when changing ndb field's property type

basically fetch underlying entity (without using ndb) - dictionary , delete key/value , save entity.

if have less 50,000 entities it's easier doing via remote api, means can without deploying new code.