If you are in an environment that has multiple versions of Flash Player, I would recommend using Adobe’s Uninstall Flash Player tool in your Flash Player install script. You can download the uninstall tool here.
Using the following line will uninstall any version of Flash Player that was installed on the computer.
Below is an example script that uninstalls and installs the latest version of Flash Player.
REM Setting Current Directory cd "%~dp0" REM Uninstalling Flash uninstall_flash_player.exe -uninstall REM Installing Flash msiexec /i "install_flash_player_21_active_x.msi" /qn /norestart /log "C:\Temp\flashinstall.log" IF %ERRORLEVEL% == 0 goto MMS exit %ERRORLEVEL% :MMS REM Copying SilentAutoUpdate Config IF EXIST %WINDIR%\SysWow64\Macromed\Flash ( copy /Y mms.cfg %WINDIR%\SysWow64\Macromed\Flash copy /Y mms.cfg %WINDIR%\System32\Macromed\Flash ) ELSE ( copy /Y mms.cfg %WINDIR%\System32\Macromed\Flash )