In the photo you will see that there are 3 trunks all forming from the base of the tree. Can I safely prune the two smallest trunks in order to promote more growth in the main trunk and an upright habit? Is this advisable? Or does it only depend on how I prefer to see the tree grow? If pruning is advisable do I do so right at the trunk, or few inches away from the main trunk? This rookie thanks anybody with knowledge for their help.