If the branch originates above the graft union, then keep the trees. That will be quicker and cheaper than replanting. You can make a new tree out of just one shoot. With an established root system the tree will grow rapidly.

Thanks for the reply!!! is there anything I should do to help promote the growth of the side brach to help its growth? maybe cut off the main trunk?

When this has happens to me I usually use the dead main trunk as a support for the new shoot. It works well to get the new shoot trained in an upright manner. Just be sure to remove it the next year.