Simply call SetActive(false) on the UI's GameObject like you do with any other GameObject you want to make inactive? Note that this system was not created to be used in this way but it might work.
If you meant to keep the Dialogue panel for example then delete the panels you do not want. Vinoma will throw an error if you delete things you are not supposed to and then you can simply undo. Candidates to not delete would be anything added to the VinomaGUI component on the VinomaGUI object.
Also note that the very 1st GameObject (panel) will be amde active. In this case "Main Menu". So if you deleted "Main Menu" then "Dialogue" would now be the one shown when it all starts up. To prevent this you can simpl yadd an empty GameObject as the 1st child of the VinomaGUI.
Have a look at the components on the child objects of VinomaGUI to see how they act. You would note for example the "AutoPanelVisiblity" component on some. Change the value as needed or remove the component if you are not removing the object but the component is forcing something you do not want.