There are multiple ways to do this. What I suggest you do, is to Go to the red triangle on the report, and select "Variability Report". Then go back to the red triangle and select "Local Data Filter". In the filter, select the variable you want to be selecting on. Then you can move between values in that variable and it will generate the new means and standard deviations, etc.
You can also turn on the Automatic Recalc option, and then select the data points you want, invert the selection and then specify to exclude the values. That will also recalculate the values. The Local data filter just does that automatically.
The documentation on this is in the Using JMP document.
Help==>Books==>Using JMP==>Local Data Filter
Jim