Hi! There is no CC# for FX on/off.
BUT...
you can send an NRPN message, which is also a MIDI message. The problem is that not all DAW send and receive NRPN messages.
If you have Max, you can do it from there. If you use Ableton, you can use this Max for Live patch to send.
https://maxforlive.com/library/device/4893/nrpn-gen-2I haven't tried this patch yet, but it looks that can do what you want to do.
You will do have to study a little if if you haven't use NRPN messages before, but it is not thaaaat complicated.