The Subtools palette is where you manage and edit subtools. This menu can be found in two locations.
In the Palettes menu, select Tool to display the Subtools menu.
This location is the first instance of the Subtools palette. The second is the previously mentioned "quick access" Subtools palette.
This is one of the most commonly used palettes in ZBrush. This icon in right toolbar offers direct access to Subtools and all its submenus.
Learn more about these options in this guide's Subtool Palette section.