You can do this with some javascript….but I haven’t done it myself.
The sidebar class you will need to update the styles for is….
.col--side
Adding….
display: none;
...to the style will hide that.
The main post section can have its style changed using this class path…
.col--main.has--side
Changing the width from this….
width: calc(100% - 384px);
...to this….
width: 100%;
...will increase its size to replace the space left by the sidebar.
To do this you will need to create a button, checkbox or something else to trigger the change. The Javascript you will need to add can go in the “Third Party Scripts”.
As I said, I haven’t actually done this (I might give it a go though, as it is a nice idea), so can’t give you the code at the moment.