If you have a Mobile Share plan, yes you can do this from the myAT&T app on your phone.you can do this by going to Usage > Data Group and selecting "OFF" on the line you want to suspend data.
If you have a tiered data plan, I would suggest disaing the data packet access on the device depending on the device you have. If it's an iPhone you can go to Settings > General > Cellular and turn Data access OFF.
*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.