Have seen this twice now. The other user was unable to "kill" the process because it continually re-launched.
Download the offline installer here: http://fpdownload.macromedia.com/get/flashplayer/current/licensing/mac /install_flash_player_11_osx.dmg
Mount the DMG and run the installer
If it won't run, go to: Mac HD/Library/Internet Plugins
Trash the Flash Player.plugin file from there
Go to: Mac HD/Library/Application Support/Adobe
Trash the Flash Player folder (the whole folder)
Empty the trash
Mount the DMG and run the installer again.