Can't remove key from ignition on 1991 hyundia Excel?

Hi just bought a second -hand Hyundai excel for my daughter having same problem, my husband has to disconnect the battery and then the key will come out easily. We have tried to press the brake to remove the key and make sure it is in Park, still will not turn from ACC to lock. A friend has suggested getting a button put in just under the lock mechanism to disconnect the battery for a few secs so we can remove the key as it will be a hassle for my daughter to try and open the bonnet disconnect battery and then run around to get key out, what a pain!! Only trouble you lose all info: clock time and radio settings every time you disconnect.