can the police officer force the boy to destroy evidence?
Not legally. Read the article. The officer can ask, cajole, beg, and plead, but not force the destruction.
Imagine this in court, "I'm sorry your honor, we had evidence but the police officer destroyed it." Every officer knows and is repeatedly trained that they cannot destroy evidence. That doesn't mean they can't encourage others to do it before it becomes 'evidence' in a case.
The details in the story are important. The officer didn't destroy the evidence. Because that would be, you know, bad. Instead he told the kid to delete it and made threats about what might happen if the boy got in trouble and the evidence were used against him.