the wiring harness broke due to collision at the front. i have the new wiring ready but how i pull it out and replace it with the new one? do i need the dismantle the dashboard to access to the connector?

What's the specific model, year etc? And can you describe which harness - is that the parking sensors and front fender stuff, or something more central to the car?

Do you have the workshop manual? Search on here / it's in a Dropbox somewhere. That gives you thousands of detailed pages of step by step instructions