iPhone X Selling iPhone X while still under upgrade program

[barcarole]

My iPhone X is still under the Apple upgrade program. I recently received an iPhone Xs from my company. So I'm trying to sell my current iPhone X.

My initial common sense is that: just sell the phone, and keep the installments until the end.

I wanted to double check. I read the terms: https://www.apple.com/legal/sales-support/iphoneupgrade_us/:

9. Trade in Outside of your Upgrade Option. You may decide to trade-in your Financed iPhone outside of the iPhone Upgrade Program for any reason (e.g., if the market value of your trade-in exceeds the outstanding balance on your Installment Loan). If you do so, you will still be responsible for any remaining balance on your Installment Loan to Bank and you will not be able to exercise the Upgrade Option as set forth above. You should also cancel the AppleCare+ Plan associated with the Financed iPhone by contacting AppleCare at: (800) 275-2273 after your trade-in.

Okay, it's obvious, but I don't understand "canceling AppleCare+".

First, yes, I can sell the phone:

• I can sell my iPhone X that is still under the upgrade program (yes, why not).
• I still need to pay the remaining installments (obviously. 0% APR; no need to prepay)

But, why do I have to cancel AppleCare+? The installment payments include the AppleCare+ already. I was trying to sell my phone WITH the AppleCare+.

So, if I cancel the AppleCare+, will I get any refund? I'm pretty confused about this term.