I didn't remove the strings when I installed the tree. I carefully removed the strings from the nut slots and pushed them aside. I removed the old tree by loosening the screw - Note: the old stock screw will not work with the new Tusq tree. The Graph Tech's Tusq tree comes with three different length screws, I used the shortest to minimize any potential damage and it worked perfect. Replace the strings in the nut groove and re-tune the guitar.
I installed these because my old trees had grooves worn in them and the string would not move freely. This groove caused a sticking point and affected the tuning in an adverse manner. The new trees counteracted this problem. My only complaint is that the new tree leaves one of the holes from the former string tree uncovered. This isn't really Graph Tech's Tusq's fault but if the base of the Tusq Tree could be made to be diamond shaped, then the hole would not be visible. Otherwise, this is a cheap, easy, and worthwhile upgrade for guitar requiring string trees.
Barely visable stabilization hole from former tree
Top view of Graph Tech's string tree
Here you can really see the hole I whined about!
Great looking function upgrade
Word of caution: be certain to double check the length of the fastening screw requirements. Installing a screw that is too long could split the wood grain and cause damage to your guitar!