AIO - Help deciding to euthanize my dog or not

I spend a lot of time in the dog rescue world and ended up with 3 large dogs I’ve had for the past 10 years. One of those dogs is territorial over its house and its people. Unfortunately I didn’t know this when I rescued him and he now has a bite on his record. He bit a neighbor years ago who was selling candy door to door and lunged at him. Fast forward a few years and I now have a 3 year old. We’ve been fine thus far and know his limitations. He guards his food and he doesn’t like hugs. Unfortunately my husband wasn’t watching the other day and our daughter hugged him and he bit her face. I didn’t know she hugged him at that time and thought he randomly attacked her over food so I went ahead and made the difficult decision to euthanize him because at the end of the day my daughter comes first and I’ve exhausted all other options for this dog for the last 5 years. His options are stay at my house in his own space under supervision OR euthanasia. He cannot go to anyone else because he will exhibit the same territorial behaviors around anyone who owns him. Since yesterday, my husband said she actually hugged him which set him off. I always tell her do NOT hug any dog. You just don’t know. Now I don’t know what to do. Do I keep him and see about training OR do I keep his scheduled vet appointment for euthanasia tomorrow? I am running out of time. PLEASE HELP!