The storage is not particular to the phones (and is not actually on them): it is online at iCloud and is accessible to any device that is signed in to that account. Just sign in your new phone in Settings>iCloud. You don't need to cancel or add any storage (unless you are using more than one account so that phones are signed in with different Apple IDs).
If you are using more than one ID you can cancel the storage on the account you don't want as detailed here: Downgrade or cancel your iCloud+ plan - Apple Support
(Using more than one account is counter-productive since the object of iCloud is not to add storage to your device (which is impossible anyway) but to allow each device to sync to iCloud so that your data can be kept the same on all your devices (so if you add a contact on one it will appear on the others) - obviously this won't work if you have them signed in to different accounts.)