@jayp welcome to the forum.
There was a recent discussion about this on this forum.
To summarise; you cannot temporarily hide the bar but you can remove both bars permanently which means the tollbars will not be available regardless of view. I am not a dev so this is just a guess but I suppose having the icons there but greyed out stops the render pane jumping up and down as you change views.
However if it is just the presence of the icons, rather than the whole toolbar itself that you are referring to, you can hide inactive icons (but the bar itself remains).
In userchrome.css add:
a.button.disabled {
display: none !important;
/* removes the disabled buttons from the note toolbars */
}
In case you are not aware there is a rather major design change in the pipeline.