You should be able to just delete the application and its associated files. This thread has a list of things and discussion of what to delete. Make sure to remove /Library/Internet Plug-Ins/AdobePDFViewer.plugin if you've installed the Safari in-browser viewer from Adobe.
Double-click the Acrobat Uninstaller file, located in the Adobe Acrobat 9 folder. Follow the on-screen instructions to uninstall Acrobat. In the Authenticate dialog, type the user name and password for an administrator account and click OK. Note: The uninstaller removes only Adobe Acrobat 9 and 9.1 files from the system. It does not remove Adobe Reader files, Acrobat user data, or files that are shared with other Adobe applications."
