I have a gorgeous 20 yr old maple that the previous owners allowed to grow wild it has 5 trunks coming out of the ground and is approx 35 ft tall and at least 50 ft around in full bloom I must prune it down a little (just a little) all my neighbours hate it how much can I cut off at one time ?
Can I shorten the height? I don't want to lose the shade or the privacy , and I'm afraid of killing it I can send anyone with advice pictures if they want I live in western canada(vancouver) when is the best time to prune , how is the best method , I have tools,ladders, etc I can do it I just need to know how
Any help is greatly appreciated thanks.

Maples are tough trees. They survive drastic pruning almost any time of year. Still, I would wait another month or 2 until the leaves are gone and the tree is dormant and you can see what you are doing. Unfortunately too many trees are topped leaving an unsightly, weakened tree. Be a little more selective. Instead of just cutting everything off at a certain height, go down a little further, and cut off the main branch just above where a smaller branch forks off leaving the entire smaller branch. This eliminates the unsightly stubs. The tree will then put its strength into the branch that is left rather than putting out a witch's nest of suckers. Once the leaves are off the trees, drive around and look at trees that were butchered that way and what a mess they are. The suckers are also poorly attached and suffer wind damage. It takes more thinking and more work, but you will have a more attractive, healthier tree.

If the tree also has exposed roots, you can cut them back too at the same time balancing the top and roots to maintain a healthy tree.

Thanks a lot for the info I was unaware I could cut the exposed roots as well there's one nasty one sticking out of the ground

I heard however that you should prune only behind the feeders ? What are the feeders? Could you explain this to me or is it just someone talking out of nonesense many thanks again

The feeder roots are mostly at the outer edge of the tree, and are the ones that actually absorb water and minerals from the soil. I don't quite understand that reference. I have hacked at maple and other exposed roots without ever noticing any damage. Perhaps I have never had the ambition to do enough at any one time to hurt the tree. Cutting exposed roots is hard on both you and your tools. Roots tend to have dirt and rocks around them. If your tools aren't dull to start with, they soon will be. Besides, most of them are made more for cutting vertical than horizontal. I have used a sharpened pickax. I usually just cut off the top half that actually sticks out of the ground. If you dug down and cut off several major roots completely, chances are you would damage the tree. Cut off the worst problem this fall. Next fall, take a little more off. If they grow back, cut them again.

A little more on roots: http://www.pixieforest.com/Alex%20Keenan/what%20are%20tree%20roots.htm.