Shaving off 8mm to 1cm from Bone Possible in Rhinoplasty?

Yes it can be achieved. However 1 cm seems to be too much. Look at your profile view and make sure you don't have a small chin. A  small chin can make your nose look bigger than it really is.
Also, reducing the nasal hump too much is more likely to lead to complications than a conservative reduction.
Regards

Newts UK, the amount of reduction performed on your nose really depends on a number of factors. One of the most important considerations is your skin type. If you have thick skin, there is a limit to how much your nose will 'shrink wrap' down following reduction of the underlying bone and cartilage. Thinner skin tends to shrink down more readily and is more favorable when looking to make the nose smaller in size. If you are able to reduce the nose by 8-10 mm from bridge to tip will ultimately depend on whether or not the final size is proportional for your face. This determination is best made through careful nasal analysis done by an experience rhinoplasty surgeon. The link below may be helpful in better understanding what goes into this type of analysis. It would be beneficial for you to undergo a personal examination followed by computer imaging of your nose to determine what would be the ideal direction and degree of change.