The antonym of "upgrade" is "downgrade", quite broadly used.
What is the antonym of "update"?
Update:
Though, I hoped for something like "un-update" because reverting or uninstalling updates are much lengthier.
Update2:
After having further answers about "Restore", et al, I decided to restore the phrase from my original update.
Yes, I can revert updates (uninstall
service packs, hotfixes or restore
the operating system to a previous
state/image)
Best Answer
If you update your browser, you might want to rollback the update or to undo it.
Mostly used in database management, I often hear/read about rollback of driver updates or program installs.