What’s the safest way to find and reduce 600 GB in AppDataLocal?

First, find out which specific folders are responsible instead of deleting things at random. WizTree or WinDirStat can scan the directory and show exactly where the space is being used. Once you identify the largest folder, check which program owns it and use that program’s cleanup or uninstall options where possible.

The contents of AppDataLocalTemp are generally safe to remove, especially after closing running applications. Windows may refuse to delete files that are currently in use, and those can simply be skipped. This probably won’t account for all 600 GB, though, so scan the directory first.

I wouldn’t use a Windows repair or reset as the first solution. It may not remove the files causing the problem and could create extra complications. If the space is concentrated in a broken user profile and you can’t identify the cause, back up your documents, browser data, and application settings before considering a new Windows user profile—but only after confirming what is consuming the storage.

600 GB in AppDataLocal is very unusual, so the folder causing it matters a lot. It could be cached data, game files, downloaded media, local AI models, browser data, or a program that is failing to clean up after itself. Don’t assume the entire directory can be safely removed.