It is very arguable it would be a crime to wipe a computer with only the police asking to warrantless search it. It's a crime to destroy any evidence of a crime so I guess there is that.

They have no evidence there was a crime though. I don't doubt they would charge it, but a jury wouldn't likely convict because it's a bullshit charge. You are under no obligation to incriminate yourself with your own evidence no matter what the police and prosecutors say.