PSA: What if someone takes down their files?

https://creativecommons.org/licenses/by-nc-sa/4.0/:

You are free to:

• Share - copy and redistribute the material in any medium or format
• Adapt - remix, transform, and build upon the material

The licensor cannot revoke these freedoms as long as you follow the license terms.

 

https://creativecommons.org/faq/#what-if-i-change-my-mind-about-using-a-cc-license

What if I change my mind about using a CC license?

CC licenses are not revocable. Once something has been published under a CC license, licensees may continue using it according to the license terms for the duration of applicable copyright and similar rights. As a licensor, you may stop distributing under the CC license at any time, but anyone who has access to a copy of the material may continue to redistribute it under the CC license terms.

 

Most cases, are similar.

You, nerfer, have a moral obligation to the sanctity and continuity of our knowledge; which is the only true higher purpose or end that any of this stuff we do can ever achieve. Now, serve your duty to protect it.

You, designer, do not take your files down. Not only is it naive to expect the community to go along with your attempt to un-pull that trigger and un-shoot that bullet, but attempting to operate outside and beyond the terms of the (strictly irrevocable) license and pressure/guilt trip people into not exercising their rights under said license (like posting copies, because you don't want it up anymore, for instance) is not kosher in any way.