You need a special kind of drill bit for drilling out spot welds. And a corded drill. And a prybar. They sell aftermarket core supports. Bolt it up temporarily and then have it welded back on.
If you want it to come out right, have it done professionally by a capable shop. Otherwise your hood, fenders, bumper, and headlights will all have uneven gaps.
I did this on a Civic Si hatchback that I had, but I wasn't happy so I sold it with full disclosure of course.
Car is pretty much a total loss IMO.
