Copper Beech Tree

This tree has been in my garden for quite a few years. I need help to decide how I should prune it as it has three trunks. Although it has been here for about ten years it is not very big, about 4feet tall.
We went up to Scourie for the library and then to KLB to the shop. After lunch I went out to the garden and continued with the work I was doing yesterday.
Quite a good day with lots of sunshine although not warm.