You didn't mention which engine you have or which O2 sensor you want to delete. A 2.2l has one in the exhaust close to the engine. A 4.3 has one in each bank of the exhaust. And they both have one after the catalytic converter.
Since you are talking about a leaky flange I'll guess the one you want to delete is the post cat O2 sensor.
You can remove it, but will likely have a SES light on all the time.
If it were mine I'd put on a new cat and a new ACDelco original equipment O2 sensor.
If the O2 sensor you want to remove is in the head pipe before the cat, it has to stay or the engine won't run very well since the computer will have no way of knowing if it is providing too much or too little fuel.
If you are in CA it would probably be cheaper to buy another truck.
Since you are talking about a leaky flange I'll guess the one you want to delete is the post cat O2 sensor.
You can remove it, but will likely have a SES light on all the time.
If it were mine I'd put on a new cat and a new ACDelco original equipment O2 sensor.
If the O2 sensor you want to remove is in the head pipe before the cat, it has to stay or the engine won't run very well since the computer will have no way of knowing if it is providing too much or too little fuel.
If you are in CA it would probably be cheaper to buy another truck.