Los Tirano
God-King
Not being able to raze cities is a problem, but you can work it to your advantage. Give the useless city to an ally, he will worship your great generosity. You can use this to create a protectorate, but you will have to be sure he doesnt like your enemies through different religions etc. If you dont he will let your enemies through his lands to attack you.
You could also give the city to an enemy. Strange i know, but every city costs maintenance, it must be in a **** position with few resources or a lot of jungle or you'd want to keep it. Could make an enemy less likely to attack, and it seems you are appeasing him/her in a big way so no cause for complaints or war. Or give it to someone recently discovered far away from your borders. On the earth map I once gave a French city to the Japanese. It really messed up european history.
Or just open the system editor and delete the city, you should have been able to raze it anyway.
Long live your Empire!
You could also give the city to an enemy. Strange i know, but every city costs maintenance, it must be in a **** position with few resources or a lot of jungle or you'd want to keep it. Could make an enemy less likely to attack, and it seems you are appeasing him/her in a big way so no cause for complaints or war. Or give it to someone recently discovered far away from your borders. On the earth map I once gave a French city to the Japanese. It really messed up european history.

Or just open the system editor and delete the city, you should have been able to raze it anyway.
Long live your Empire!