Yeah.... When you have a mixture of evaluating and non-evaluating cells selected, the behavior of the Cell > CellProperties > Evaluatable menu isn't obvious. I think the two states the OP wants to toggle between are:
- set Evaluatable to False for the currently selected cells, or
- reset the Evaluatable setting back to the default for those cells.
That's trivial to do with the option inspector, but it's just as easy to generate a palette to do this:
Button["Turn off Evaluatable for Selected Cells",
CurrentValue[SelectedCells[InputNotebook], Evaluatable] = False],
Button["Reset Evaluatable for Selected Cells",
CurrentValue[SelectedCells[InputNotebook], Evaluatable] = Inherited]}]]
This palette can even be installed with the Install Palette item at the bottom of the Palettes menu. Then it'll always be there in menus when needed.