Q: remove pages 2013

Open a Finder window, choose Applications in the sidebar and drag the new Pages version to the Trash. Then, empty the Trash.

Before deleting the new version, you have to export the documents you used with it to Pages '09, so open these documents with the new Pages version and go to File menu (on the menu bar) > Export > Pages '09.

Also, I don't recommend you to delete the new Pages version, because the Mac App Store will ask you to install it. Instead, you can leave it and update it when Apple releases an update, so you can decide if you want to use it or the old Pages version

The ( my ) problem is, that after updating the old pages to the new version...the old one doesn`t open again!!!???

I´m asked for the licence-number...which is on the backside of my iwork`09 familiy package...but it is not accepted by the appstore...?

The retail box of iWork '09 does not require a serial number. Getting the request for a serial number means that at some time you had the iWork ’09 trial installed. You need to delete the trial & then reinstall from the boxed DVD or the Mac App Store. The files to delete are the iWork ’09 folder from the main HD > Applications; the iWork ’09 folder in HD > Library > Application Support & the individual iWork application plist files found in HD > Users > (your account) > Library > Preferences for each user. The easiest way to fix the problem is to use Yvan Koenig's AppleScript that removes the files. Yvan's box.com account often is out of bandwith. I have put a copy on my Box.com account in the iWork folder. Download uninstall iWork '09.zip, decompress it, open it in AppleScript Editor and click the Run button.