Using scenario editor, I created a town near waters and put an oil rig in waters.
When I try to delete town, now it refuses that it has station or objects using city name. It do not let me delete oil rig also in any way. I renamed oil rig also to give it separate name from city name it inherited but no success.
I have many other towns and industries in the scenario so starting a new scenario is not the best option.
Let me know if I can just delete couple of towns with oil rigs.
Best Answer
I'm unable to reproduce your problem in the latest release of Open TTD, 1.3.1.
Creating a body of water, neighbouring town and oil rig I see that as you say you can't remove the town because of the associated oil rig, however it is possible to remove the oil rig using the demolish (bomb) tool: