rmvar
              Remove an input or output variable from an existing FIS structure and return the updated FIS.
The types/values of the arguments are expected to be:
| Argument | Expected Type or Value | 
|---|---|
| fis | an FIS structure | 
| in_or_out | either ’input’ or ’output’ (case-insensitive) | 
| var_index | an FIS input or output variable index | 
Note that rmvar will allow the user to delete an input or output variable that is currently in use by rules in the FIS.