As I travel through the newer neighborhoods I notice that so many trees look like their being held captive for growing to maturity. It’s not the trees’ fault for what happened; it’s just part of the natural cycle of things.
The general rule of thumb is when the tree trunk becomes the same size as the stake in diameter then the stakes and the straps can be removed. If the tree has a problem supporting itself and wants to fall over then it would be better to remove it and plant another. More than likely, if the tree has been in the ground for at least a couple of years the roots are probably girdling around themselves or it was a poor specimen to begin with.