do so knowing that the evidence is to be produced during a legal or court proceeding
If they haven’t accused you of anything yet, deleting “how to rob banks.txt” is just normal cleanup. Anon can’t know what might be relevant evidence after some cops ask to see his computer and leave. Of course, some files may have legal restrictions regardless of crime, for example financial records.
I’m very glad you’re not a lawyer.
https://www.shouselaw.com/ca/blog/destruction-of-evidence-charge/
This says you just need to know what you were destroying was evidence, which Anon clearly does.
If they haven’t accused you of anything yet, deleting “how to rob banks.txt” is just normal cleanup. Anon can’t know what might be relevant evidence after some cops ask to see his computer and leave. Of course, some files may have legal restrictions regardless of crime, for example financial records.