Disable GPRS and UTMS?

[Mento]

How can I disable GPRS and UTMS? I mean realy disable, so I cannot use it anymore. (or someone else)

[madkat]

Option 1: Ask your service provider to disable Data on your account,
Option 2: Delete the settings and don't lend your device to anyone,
Option 3: Use a different device.

Why would you want to permanently disable GPRS and UMTS on a device which has those as one of its selling points?