Ofdm - adjust subcarriers

Hi out there,

I’m trying to send an ofdm signal. I don’t want to tramsit any data, I
only
want to see the reslting spectrum.

Now I’m wondering how to turn off certain carriers.

I know this is possible by adjusting the transmitted data but is there a
better way to do this?
For example by commandline?

Hope someone can help.

Hanno