You will need to slowly bring your total daily insulin amount down as you reduce your food intake to lose weight. If you don't do this, you will experience cravings and hypos, either of which can easily defeat your weight loss. Ideally you need to slightly reduce your total insulin dose the same day or the night before you start to reduce your food intake (primarily, your carbs).
As you progress in losing weight you will need to continue gradually reducing your total insulin intake. Partly this will be because your body weight is less, partly because your insulin sensitivity will improve, but mainly it's because you are eating fewer carbs. If you don't do this progressive reduction in insulin you will struggle to lose weight as a T1. But obviously don't overdo it. Test more regularly than usual while dieting, and be mindful of your basal dose and your various insulin ratios - insulin to carb ratio and insulin correction ratio. These will all need to change - but gradually.