There is no Out Of Box(OOB) feature to hide the quick launch menu items or tree view navigation in SharePoint site.
Let's assume that you have created a intranet site for your organization and you want that all users should view that site in full width mode. As you have lot of tabular content on it. How to go about it?
Let's a assume that you have created a team site.
Next thing you have to do is edit this page and add content editor web part
Click on "Add a Web Part" and select "Media and Content" in the categories section and then select "Content Editor" in WebParts section and then click on add button(as it is highlighted).
Now you just have to paste the following code in web part
Go to Editing Options ribbon menu, select Html DropDown button in Markup menu item and then select "Edit HTML Source"
and paste the below code in it.
And now you can see that there is no quick launch menu items :-)
Most of the times old tricks works ;-)