Something to keep in mind:
None of the tools in the Tool palette’s popup window can be used for sculpting. So hiding any of them doesn’t make much sense. Here’s the philosophy:
To select something to draw, use the Tool palette popup.
To edit something once you’ve drawn it, use the Transform palette to enter Edit mode and then use the various sculpting tools that will become available there. You will NEVER use any other tools to edit the currently-selected tool (unless you’re using Projection Master, and you should run its tutorial to learn more about that).
In addition, the Tool palette will change depending upon what type of tool you have selected. So if you have a 2.5D brush selected, the Tool palette will only have modifiers that can be used on that brush. If you have a parametric object, then things like the Deformation menu become available. If a polymesh object is selected, the Geometry menu gets some new features, and if it’s a ZSphere model you’ll have the Adaptive Skin and Unified Skin menus. In other words, ZBrush already changes itself to make just the options available that you can actually use for the currently selected tool.
So it really seems to me that your question stems more from a misunderstanding of how ZBrush works than from an actual need. 