I have got the strainer disconnected from the pipe and have scored around the bottom of the strainer getting all the old putty off but it won't budge. I even hit it with a hammer all around it and it hasn't moved. Any other suggestions.
Start by removing the pipes that are connected to the old sink strainer.
Once the fittings are out of the way remove the old strainer nut with a large pair of pliers. This can be a little tricky sometimes. If you cannot get a good grip on it you may need to cut the nut out before you can remove the strainer. After the nut has been removed you can pull the old strainer out from the top of the sink.