I just wanted to revisit this thread, re: letting my Kasikorn ATM card lapse. I let my ATM card lapse and there were no further yearly 300 baht fees deducted and I did not notify them of anything. I do get charged 20 baht a Month for SMS alerts but it is not necessary as you get push notifications on the app.
About ATM QR code cash withdrawals. This is the best and most simplest way to make withdrawals of cash. So I walk up to my ATM, I have the app open and the cash amount ready to go, I press cardless cash withdrawals on the ATM then KPLUS and a QR code pops up, I scan it on the app, touch correct on the ATM and out comes the cash. It never failed and only took 15 seconds to do. Did is several times during my stay, very fast and the way to go. Thanks for all the advice people.????