Excluding cases where uploaded content violates our submission guidelines or is otherwise deemed unacceptable within the Download Center, user-submitted content cannot and will not be removed later. In order to ensure that any mods which depend on other content remains playable, and to ensure that users can continue enjoying user-created content, we require that any submitted files are permanently available. This includes previous versions of files as well as the entirety of the file itself.
You may be wondering - why? Shouldn't the mod author be able to dictate what to do with their own content?
There have been cases where mods for other games on other platforms have been taken down by the author for various reasons - and as such, users must either seek out old downloads that other community members had lying around, or simply be unable to use their favorite mod anymore. Among other things, Elaztek Studios believes in preservation of content of all sorts. We believe that users should never be locked out of things they enjoy, or forced into a different user experience for no good reason. And while we do generally wish to place as much control as possible into the hands of the user, this is a special case where allowing mod authors to remove their own content is far more damaging than restricting this ability.
You don't have to continuously support or update your mods as an author - that's not what we're saying. You're entirely free to add a note to your file stating that you are no longer updating the content. However - we believe that people should still be able to use that old, unsupported version of the content - after all, there's nothing stopping them from just using an older build of the game, so there's not much to stop them.
The tl;dr - once your content is submitted, there's no take-backs. Once it's shared, its shared - and unless we end up removing it ourselves due to violating one of our guidelines, it can't be taken back offline later.