where'd i turn off data usage so there's no way it can be turned on accidently or limit the usage to zero?
**Edited to add label
If you wish to prevent all data usage, you should be able to disable data altogether. The exact steps to disable (or enable) data vary slightly between the different phone models. For iPhones, try Settings --> Cellular --> unselect Cellular data. For android phones, try Settings --> Networks --> Mobile Network --> uncheck Mobile Data. Unfortunately, there's no 100 per cent sure proof way to prevent accidentally enabling data. Some phones may have short-cuts to enable/disable data. You will just have to be vigilant when adjusting your settings.
If you do not wish to use data, do you have any data with your plan? If you do not have a data plan, I believe you will be sent a text requiring you to accept the purchase of a data pass or plan prior to being able to use data.
Hope this helps