Some things would be simple, like removing the wlw manifest link, shortlinks, meta generator, and other elements that give a site away as being wordpress.
But, that still leaves some giveaways that are harder to deal with, like the url structure for uploaded images, urls for admin panel, other known urls like /wp-feed.php etc. There are a literal ass-load of these.
There is a plugin called "hide my wp" that supposedly addresses some of this Can't vouch for it. It's $22.