On second thought it’s easier to change Google and FB. Give them 6 months to enable people to remove their stuff or face a $1000 fine per day, per user.
It's not Google or FB, it's all that permanent record stored on servers throughout the world.
If Google wasn't the search engine there would be some other search engine to find it.
Changing identity isn't a solution either since I suspect it would eventually be easy to connect new ID with old ID.