Really? Maybe the second could be considered obstruction, but in the first case you'd hold that once one has any concern about anything ever viewed online that it is forever illegal and a crime to delete? Who would you even go to if you wanted to clear yourself to repurpose your computer? Would you have to hire counsel for an opinion regarding the legality of deleting anything regarding the acts in question?
Regardless of whether it is or is not actually illegal, it shouldn't be a crime short of being under an active investigation. I'd go further and require an actual injuction to be issued prohibiting your free exercise of your rights to your own property. The destruction may be used as circumstantial evidence at best, which would be weighed against whatever plausible motivations you advance for your actions.