Salesforce makes it hard to delete classes in a production org. Our change control policy doesn’t allow for the use of the IDE to make changes to the production org…everything goes through change sets for traceability to th original request.
How do I delete a class?
Answer
This can be done with the Force.com Migration Tool: http://wiki.developerforce.com/page/Force.com_Migration_Tool
See the full documentation here: http://wiki.developerforce.com/page/Force.com_Migration_Tool
The tool can create or delete any meta-data that can be created through the Force.com IDE or Change Sets. It comes with a sample config file that contains example deployments for deploying objects and Apex code and deleting them as well. The documentation has a very detailed step-by-step guide here: http://www.salesforce.com/us/developer/docs/daas/index_Left.htm#StartTopic=Content/forcemigrationtool.htm
Attribution
Source : Link , Question Author : Shane McLaughlin , Answer Author : E.J. Wilburn