cannot delete grading projection daylight lines

[pics.munmun]

i created some grading and then deleted them. 

Some of the lines did not get deleted (refer attached images)

how to delete them?

[Anonymous]

I've had luck deleting the grading object from the prospector tab in toolspace. If you deleted the grading object in model space, and the grading object is removed from toolspace while the daylight line persists, then I'm not sure what to tell you - other than I wouldn't be surprised.