The Data capability can be turned on/off via the Settings menu of the mobile device.
Go to Settings > Mobile Network > Mobile Data Options:
Toggle the “Data Roaming” option.
Go to Settings > Connections > Data usage:
Toggle the “Roaming Data” option
The Settings menu can differ per type of mobile device and/or version of the operating system of the mobile device, we recommend that you consult the manual of the mobile device for this.