Could you reduce the weight of a Santa Cruz Chameleon down from 12.82 kg to 10kg (2018 model)? I am currently thinking of getting my first mountain bike, I have ridden a lot of cyclocross and am used to a 10kg bike but am not that familiar where you could save weight on a mountain bike.

What components would you use to reduce the weight of a 2018 Santa Cruz Chameleon which currently retails at 12.82 kg? I would mostly be riding rough cyclocross races and XC races. I would be purchasing a large frame size.
Breaking the rules with a kind-of non-answer and personal opinion, but...

1) Mountain bikes should be heavier than a cyclocross bike. It's got a suspension fork and frame and wheels need to be beefier to handle bigger loads and impacts. 

2) Don't buy a bike with a plan replace major components. Just buy the bike that meets your needs in the first place (in this case a bike lighter than 12kg out of the box). Doing so will be much, much cheaper than swapping out parts.

Another way of stating (2) is: there is only one component you need to swap out for a lighter alternative - the bike itself.

I note the higher level SC Highball S hits your weight goal.