peteroznewman
Subscriber

This thread has a solution which I copy/pasted into my reply.  I have not tried this myself.

I found that if you go to the variable that you are using for the input parameter and then uncheck the "use as input parameter" checkbox, save the project, then go back and check the checkbox and it should clear up the unused parameter.
I also found that in the case where you delete an expression or variable that you used as an input parameter it will not delete it from the Workbench parameters list. To get around this, remake the variable that you deleted, i.e. if you deleted a variable, that we'll call X1, that was an input parameter, remake the variable X1 but this time don't check the "use as input parameter" checkbox, save the project, and it will be deleted from your parameter list in Workbench. Then you can go back and delete the variable again.