Dropping Variables
When dropping variables from the pipeline while debugging the service, keep the following points in mind:
You can only modify the pipeline when a subsequent step in the service exists to which to pass the pipeline values. You cannot modify the values of the pipeline after the service ends. However, if you debug the service using the step commands, you can modify the pipeline values for the next flow step in the service.
When drop variables from the pipeline, the changes only apply to the current debugging session. The service is not permanently changed.
You can only drop existing variables. You cannot add new variables to the pipeline.
You can only change the pipeline for the top-most stack frame in the debug session.
To drop values from the pipeline while debugging
2. In the debug session, use the step command or a breakpoint to reach the step for which you want to drop a pipeline variable.
3. In Variables view, select the variable you want to drop from the pipeline and click 
on the Variables view toolbar. Designer removes the variable from Variables view. 4. Continue debugging the service using the step commands or selecting Run > Resume.