Contact Citizen One and payoff the loan with them. However you will no longer be in upgrade program. If you want to upgrade to X using upgrade pre approval process, upgrade to X, but when time comes, do not turn in your 7+. You will have 2 loans. Once X is in your hands, contact Citizen One and pay off loan on 7+. You will then only have loan on X. That way is the best if you do not want to mess with new loan enrollment process on preorder day.