You can use options within the Design Tool to detach event handlers from Host Integrator components. If you also want to remove associated files, additional steps are required.
Detaching an event handler
Removing an event handler file
You should check for the presence of any other component using an event handler before deleting it. Use the Type tab in the Attach Event Handlers dialog box to review any components that may still be using the event handler in question. If you delete the .java file when an event handler is still attached to a component, the event handler will be displayed in red in the Attach Event Handlers dialog box, and you will be warned when you try to save the model that it cannot be deployed in its current state.