SQLFreeEnv(environmentHandle);

Populate a combobox control with a list of DSNs, uses SQLAllocEnv and SQLFreeEnv

        SQLFreeEnv(hEnv)

            SQLFreeEnv(environmentHandle);

static extern short SQLFreeEnv(IntPtr EnvironmentHandle);

Declare Function SQLFreeEnv Lib "odbc32.dll" (ByVal Handle As IntPtr) As Short