Hi Maple, DO NOT prune the maple tree! all Acers will bleed profusely if pruned in spring. wait until late summer or even early autumn, and even then only on young trees.
Hazelnut trees are not so specific and can stand a good prune, but it will affect the crop. you need to keep the "scaffold" branches, and take out the stronger competing limbs. It is quite a complex tree and I could go on for hours about them, but i won't. Don't hesitate to let me know if you need anymore advice.
Bryan.