How do I turn off closed captionis from my digital TV?

How do I turn off closed captionis from my digital TV?

I have a 42" Soniq Plasma TV, model RC606. It was purchased from JB Hi Fi, I think its a Samsung plasma core.

The HD digital set top box is a DGTEC. No model number is on the device. The remote for this device does not have a subtitle button but it does have a TTX button.

Any advise you can provide regarding removing the captions from normal television and adds would be fantastic.

I appreciate your response.