problem in deleting layer in pads layout 2005 ??

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    Hi everyone, our team did board 6 layer unfortunately  layer assigned from 1 to 8. i tried to delete the layer 7 and 8 it is not deleting i got some error.Please help any one to solve this problem ??

    how to delete layer 7 and layer 8 .it is almost over. i could not delete the object is it possible to solve ?