Welcome to the community!
What plan type do you have? Many of Fido's post-paid plans include Fido Roam. However, you should note that it is not available with their post-paid Basic plans nor pre-paid plans. Fido Roam would allow you to use your plan's included minutes, messages, and data while abroad for a daily fee (see here).
If you did not wish to used Fido Roam, you would need to contact customer service to opt-out of the feature. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above. It should be mentioned that if you opt-out of Fido Roam, any usage would be on a pay-per-use basis.
You should note that the US has shut down their 3G networks so you would need to ensure your device is capable of voLTE (see here). As a result, you should also note that US roaming is no longer available with Fido pre-paid plans.
Hope this helps 😀