Help! Change body comp without affecting lean muscle?

Another vote for heavy lifting. It seems to be the biggest bang for your buck compared to any other method I've ever heard of. (some of them were complete woo, others legit, but still heavy lifting wins)

I agree with what the others are saying, but maybe in a bit more detail.
The most important is to create the caloric deficit, and set the weight loss to something tolerable at first, like 1 lb/week. If you go too fast you'll be pretty miserable trying to adapt to such a sudden change. (speaking from my experience).

Protein intake works well for me at around 1g/ lb bodyweight. I have tried going lower, 0.7-0.8g, but I lost muscle in a matter of 2 months. Of course this depends highly on how you train. The more you train, the more protein you need. I train 5-6 times a week. I know some who get away with 0.8g and they train 3 times a week.

Heavy lifting is definitely good - specifically in the 6-8 rep range. For me, I see it as you telling the body that you still need the muscle, so it won't use it for energy (since you're in a deficit). Pretty crucial in muscle retention imo