They have come out and said that you MUST delete it, otherwise files from downloading the official game may become corrupt etc.
Uninstallation of the Beta Client After the Completion of FINAL FANTASY XIV Open Beta Test After the Open Beta Test comes to an end, please uninstall the client software "FINAL FANTASY XIV Beta Version."
Installing the release version of “FINAL FANTASY XIV” or other software developed by our company while “FINAL FANTASY XIV Beta Version” remains installed may cause certain issues. Should you try to uninstall “FINAL FANTASY XIV Beta Version” after installing the release version, certain settings may be reset.
Edited, Sep 20th 2010 5:35pm by SpikeoElward
Spikeo 75 RDM - Gilgamesh - Retired