I have two ropes already tied to the ladder legs ..... one on the left and one on the right. The top of these ropes are tied to the first or second rung below the seat. These ropes are crossed behind the tree. The other end is tied about 2/3 the way down the ladder, and cinched very tightly in place. This is part of how I secure the ladder to the tree .... in addition to the top end strap(s). Once I take the top strap(s) off and untie the ladder stand-off brace, I will carefully untie the criss-crossed ropes at the bottom. I then ease to the backside of the tree and use these two ropes to control the rotating of ladder down. Most of the time I can get the ladder all the way to the ground gently, but sometimes I get the top to within 3-4 feet and the bottom kicks out and the ladder drops those last few feet. I have never had any damaged using this technique.
The only time this is really tricky is when you are working a ladder down that has been set up to look down a steep hillside ito a bottom.