Hi Pepe,
At the moment you need to call the Minimizer::Clear() method to clear the parameter states and re-set them as free ones. You can save their values and step sizes (using the errors) from the previous minimization) when you re-set them.
The opposite, setting first a parameter free and then limited is possible, just by calling Minimizer::SetLimitedVariable the second time.
I need to fix this to make possible to set a parameter bounded and then free.
Best Regards
Lorenzo