Reverse the procedure and use the car fairly often. Otherwise, if you are able to park off-road, then putting the battery on charge using a smart charger for 24-48 hours as often as you think may be required is the best way to protect the battery through the smart conditioning process.
Thanks for your replies.
I don't think insurance relies on having an alarm unless, perhaps, you have gained an extra reduction for it. I imagine the immobiliser will still work, as that is associated with a particular key.
I have yet to investigate the manual locking but can cope with the other suggestions, except when we leave it to go on holiday.
All that said, Kia offer this as a battery saving facility, so it seems strange that it is not more practical to use.