There was a question on the Autodesk Inventor Forum, about a missing command that will make it possible to switch the driven Dimensional Constraint in the Inventor Sketch Environment with another Dimensional Constraint.
In this movie I show you the command "Switch Driven Dimension".
After the command "Switch Driven Dimension" is press you are asked to select the First Driven Dimensional Constraint.
Than you are asked for a second Non Driven Dimensional Constraint. These two Dimensional Constraints are then tried to be switched.
When the first selection is a non driven Dimensional Constraint, you are warned that this is not a driven dimension.
Maybe this is a good idea to implement in future releases of Autodesk Inventor.