I am not sure if there is an API function to change the Windows virtual memory settings, but you should be able to simply modify the appropriate registry key to do what you want.

Key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management

Value:
PagingFiles

The data type is REG_MULTI_SZ and the format is:
<location> <initial size> <maximum size>
i.e. "C:\pagefile.sys 1344 2048"

Setting the data for the above value to an empty string would result in setting Windows to not use a paging file. Of course a reboot would be required after modifying the registry key value, just as it would be if you changed the settings through System Properties, etc.