You can keep your preset list clean by deleting unwanted custom presets.
 How to delete a brush preset
How to delete a brush preset
                                                            - In the Tools toolbar, select the Brush tool or press Alt + B. 
- In the Tool Properties view, select the brush preset you want to delete.
- Do one of the following:
- Click the Delete Brush
button.
- Open the Brush Preset menu
and select Delete Brush.