Hi Altaf,
To delete CoA, go to edit chart of account and select GL account and right click on it and select advance and choose delete. But this you need to do one by one for Each GL account or you can select Title GL account and right click on it and select Advance and choose delete it will delete all sub levels of that Title Account.
But best way is what Johan Hakkesteegt has suggested you in above post.
Thanks,
Harshal