Remove Setup Bootstrap folder on SQL Server 2008 to free space

Is it "safe" to delete any of the subfolders in C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\ from my drive to free up space?

Or is it needed for upgrade/uninstall and other patches? Right now the Update Cache folder contains KB968369 (sp1) which takes up 416mb, which seems like a candidate for freeing up space.

According to this site, you shouldn't. You can compress it and remove log files, but you shouldn't delete it.

If I hadn't googled for it I would probably have tried searching to see if any of the files were open, and if not, then copied them to a new location for storage until I was certain the server worked well without it, and if there was an issue recopy them over.

Then again I also have been known to delete the hidden/compressed update files in the Windows directory which is also considered bad practice from what some have said and have had no horrible side effects while freeing up hundreds of meg in space.

An alternative would be to look into installing larger drives and expanding your disk partitions. Depending on the role of the server this could be a major project, though, but in the end if you're in need of freeing space on a database server it's probably time to look at upgrading that subsystem, at least.

An alternative solution if you're low on disk space, would be to move the contents to a new directory on a different drive/partition, then use mklink /j to create a junction. More info on junctions can be found here https://msdn.microsoft.com/en-us/library/windows/desktop/aa365006(v=vs.85).aspx

From Microsoft site:

If the Update Cache folder or some patches are removed from this folder, you can no longer uninstall an update to your SQL Server instance and then revert to an earlier update build. In that situation, Add/Remove Programs entries point to non-existing binaries, and therefore the uninstall process does not work. Therefore, Microsoft strongly encourages you to keep the folder and its contents intact.

I think, it depends totally on your situation. I have two SQL Server Express instances running currently for development. One is 2012 instance which is old, as I will not remove patches installed long ago and probably no new patches will be available, I will remove files from this directory. If problems occur for future updates uninstall and install again will be pussible, I guess.