Searching for "remove Timeline" or "disable Timeline" on Facebook returns more than a dozen pages and groups that claim to have instructions on how to disable the new Facebook feature. Every single one of these "instructions" are fake, and ultimately con users into various scams, such as randomly like-ing pages or downloading a browser extension.
Once the user has agreed to try out Facebook, there's no going back. It's a permanent change, and it will become mandatory across the site eventually. Users who think they may not like Timeline are better off not bothering to try it out at all for the time being.
For the privacy-conscious, Facebook does offer privacy settings to customize what is visible on Timeline.
If the user has switched over to Timeline and is really unhappy about all the long-forgotten wall posts and photos being resurrected, ZDNet's Zack Whittaker recommends using macros and a Greasemonkey script to delete the content semi-manually from the site.
"Because the Timeline's switch is fully in the 'on' position, you cannot go back. You're stuck," Whittaker wrote. However, with some time and effort, "and a great deal of trial and error work," it was possible to delete the data, he said.