It depends on the size of the tree. Remember that whatever height it has reached, its roots will have spread half that distance again all around. If it's a huge tree, you may be better employing tree surgeons to take it down. Check with your local authority first in case you need permission. Many trees are protected.
If its a small tree that you can dig out of its current location and re-plant in a better position, wait until early winter when the tree has gone dormant before attempting to move it. That way it stands the best chance of survival.