Question
I have several conifers edging my garden,but the roots are distorting the wall adjacent.If I take some height off and clip the foliage back will this stop the roots from causing more damage?

Answer
Probabally not. The best way would be cut the roots with a trench along the wall this would keep the roots from damaging the wall. Ofcourse this depends on how far away from the wall the trees are and if you have room to cut the roots. If the trees are small 5-6 feet tall you may think about transplanting them OR just starting over with trees further away from the wall. With the information you provided I would go with the root cutting.
You can trim Leyland Cypress (like a "christmas" tree). But the foliage will grow back and the roots will still be there.