Step1-Hard reset Grand 2.
Step2-Now root it using Cwm.
OPEN SUPER SU app then it will ask to remove know nw click ok,If it will take more that 1 minute then again goto cwm and root..
Now open Super Su,then it ask to remove know,Click ok...
Step 3-download system app remover;Open It,Grant root Access,
Search 'Knox'
NOW remove all apps that are related to Know(Whose name starts with Knox)....
Step 4(If u want to download to Nh6)-Open Odin Flash firmware ,It will stop...
NOW.turn off grand2 Open again in download mode ::::again flash firmware...
Done.......
REMEMBER 1 THING:after reset or in whole process DONT OPEN KNOW app.....

I hope it helped you...
Step2-Now root it using Cwm.
OPEN SUPER SU app then it will ask to remove know nw click ok,If it will take more that 1 minute then again goto cwm and root..
Now open Super Su,then it ask to remove know,Click ok...
Step 3-download system app remover;Open It,Grant root Access,
Search 'Knox'
NOW remove all apps that are related to Know(Whose name starts with Knox)....
Step 4(If u want to download to Nh6)-Open Odin Flash firmware ,It will stop...
NOW.turn off grand2 Open again in download mode ::::again flash firmware...
Done.......
REMEMBER 1 THING:after reset or in whole process DONT OPEN KNOW app.....

I hope it helped you...