4 possibilities come to mind...reserving the right to scratch some of these from the list, pending pictures...
1) From an aerial lift (bucket truck...).
2) By climbing the tree (tied in twice, using all appropriately-rated for life support equipment).
3) With a pole saw.
4) Hire somebody to do one of the above.
You may have noticed, there is no mention anywhere of any ladder on the list at all...that was on purpose!