What are Delivery Optimization files?

Short answer: Delivery Optimization keeps pieces of Windows and Store updates to share with other PCs. They are safe to clear; Windows downloads again what it needs.

By hand, with Windows' own tools

Open Settings > System > Storage > Temporary files, tick Delivery Optimization Files, and choose Remove files.
To share less: Settings > Windows Update > Advanced options > Delivery Optimization, and turn off downloads from other PCs.

With Sparewise

Shows how much space they use, as Windows leftovers that are safe to clear.
Points to the Windows setting that clears them.

Questions

Is it safe to delete Delivery Optimization files?

Yes. They are copies of update pieces; Windows downloads again whatever it still needs.

Get Sparewise, free

Get it from the Microsoft Store or download the installer

Free · Windows 10 and 11 · No account · No telemetry · Everything it removes can be put back

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