Question
I moved into a house with two overgrown apple trees in our backyard.  The other owners must have cut the lower branchs at some point, becuase it is very high.  You can't pick an apple from the ground.  Can I trim the tree down from the top.  I had a friend that cut a pear tree in 1/2 from the top down. It looked funny for a few years but now it is a nice tree.

So can I cut it?  :)

Answer
Kris,
This type of pruning called topping, is frowned upon by the arborcultural world. It creates unsafe conditions in the formation of secondary sucker growth which is much weaker than the normal branches.
I would recommend that you perform a technique called drop crotching. This is a process where you locate the tallest  branches and remove only a few at a time. This allows the other growth to fill in naturally and stronger.
Good luck.
Ed Gulliksen