64 bit - run %systemdrive%\Windows\SysWoW64\odbcad32.exe
32 bit - run %systemdrive%\Windows\System32\odbcad32.exe
Like many people, you got your bits-vs-folder confused, because of Microsoft's insane naming scheme. SysWow64 means "Windows 32-bit on Windows 64-bit", and is the folder that holds the 32bit executables and DLLs for use on a 64bit OS. System32 kept it's historic name, even though in 64-bit OSes, it's the directory for the 64bit system files. See File System Redirector in MS online docs for even more.