The tree is dead, has declining health, the tree is beyond repair because of storm damage, tree is too close to bulidings, utility lines, play structures, pools and etc. If the tree is leaning towards an obvious target such as a house, driveway, patio, play area or pool. When tree roots pose as a serious threat to foundations, driveways or sidewalks and underground utilities. Major landscape renovations that would either damage tree or not match well to its location.