The blocking for a fixed or random effect is usually included in the design. How was the design blocked?
If you used JMP to design your experiment, for example Custom Design, then the blocking effect would have been properly represented with a term in the model that was is automatically included in your linear regression analysis. Which type of design did you use?
In fact, even f you deem that the blocking effect is null then you should not remove this term in the model, as blocking introduces a restriction on the randomization of the experiment. The blocking of runs is always part of the analysis.
How many runs are in your design with replicates?