Can mold on bread be killed with heat so it is safe?

No. Once mold has formed, throw it away.

To add a little detail... yes, you can kill the mold, but that won't make it safe. The mold produces substances that are toxic to us, so even if the mold is dead, you don't want to eat it. I don't know if this is a strategy the mold has evolved for keeping all of its food for itself, or if it's just that way.