Uninstall

brew uninstall --zap orthant

--zap is the complete removal. It deletes the app, its preferences, caches and saved state, and revokes its Accessibility grant. A plain brew uninstall leaves those behind. If you reinstall after a zap you will be asked for Accessibility again. That is the grant having genuinely gone, not a bug.

What an uninstall cannot remove

If you enabled “Launch at login”, that registration survives the uninstall. macOS records it in a system database that Homebrew’s uninstall step does not manage, and by the time the removal script runs, the app that could have unregistered itself is already deleted. (A future version could unregister itself from a step that runs before removal; today it does not.)

To clear it, turn off “Launch at login” in Settings ▸ General before uninstalling. If you have already removed Orthant, the leftover entry does nothing, because there is no app for it to launch, and installing Orthant again will pick the setting back up.

Uninstalling a manual install

Quit Orthant and delete the app. Settings live in ~/Library/Preferences/app.orthant.orthant.plist, and the Accessibility entry can be removed in System Settings ▸ Privacy & Security ▸ Accessibility by selecting the row and clicking −.