It is a pain when you create a new wiki page and you just want it to look like the default page, but it doesn’t because its got this Recently Modified section on the top of the Quick Launch. Here is how you get rid of that eyesaw:
Add a CEWP to the page and switch to the HTML/source view of the web part
Paste in this style override:
Save the page and navigate away, then back to see the section gone.