Presets allow you to save & reuse styles. This is useful, for instance if you have a website with a certain image style. You just create the preset once in Picturesque, and no matter what other effects are applied, you can go back to it at any time.
The Presets Panel
Remove Preset - Deletes the selected preset. This cannot be undone.
Overwrite preset. - Maybe you want to edit your preset, by changing an effect slightly. Select the preset, change the effect, then click overwrite to save your changes into the selected preset.
Revert to previous settings. - If you had been editing an image in Picturesque, then chosen a preset, your previous effects will be gone. Thankfully you can revert back to the state of Picturesque prior to when you opened the presets panel.