Of course. If you purchased iWork applications in the Mac App Store, you can install them as many times as you want in all your computers for free, so you will be able to reinstall them after deleting them. To do this, open the Mac App Store, go to Purchases and download these applications
To delete the apps, simply go to the Applications folder and delete them. To move them to an external drive, simply go to the Applications folder, select the iWork apps with the Command key and press Command and C keys. Then, go to the external drive and press Command and V keys
I went ahead and deleted Pages 5.0 to go back to 4.3. I can update back anytime I want. The same way I did it before. Only problem, Pages 4.3 keeps crashing. Must be something do with the compatibility with the Mavericks OS.