If you want to train it to an open center, then you will need to remove the central leader eventually. It is better to do that now than to wait another year or two. It will be a large cut, so I suggest waiting until there is about a week with no rain or freezing temperatures in the forecast. I assume the diameter of the central leader is a few inches thick, so you will need to use a sharp pruning saw to remove it. Start by removing some of the top growth on the central leader to remove some of the weight of the branch, this will ensure a cleaner cut. The cleaner the cut the quicker it will heal. You will want to end up with a tree that has no central leader and 3-4 scaffold branches that branch out in different directions (i.e. not all on one side of the tree). Select the branches that have the widest angles where they attach to the trunk, and keep those. You can remove all of the other branches. It is hard to give more direction than that without seeing the tree. 
You can find more information on training and pruning in this OSU Extension publication: https://extension.oregonstate.edu/catalog/pnw-400-training-pruning-your-home-orchard. The Lane County Master Gardeners offer a series of pruning classes starting in January. We are still confirming dates and locations, but the schedule will be posted to our website by early December: https://extension.oregonstate.edu/county/lane/events

This is very helpful. I was afraid of having to make the big cut, but I was pretty sure you would say i needed to do it.