How to uninstall Numbers and Keynote on Mavericks?
I recommend you just delete Numbers and Keynote using Finder.

The Mac App Store will detect the missing apps and allow you to reinstall them in the future if you ever need them.

Alternatively, you can use AppCleaner to delete them. This will remove all associated preference/cache files. This is usually superfluous unless you have an actual need to delete the preferences. They're not doing any harm leaving them there.