The MySQL server doesn't process statement batches; it only recognises single statements without terminating semicolons.
However, some client programs, like the mysql client, and apparently phpMyAdmin as you point out, accept statement batches, which they parse into individual statements and send individually to the server.
I don't know much about PHP, but I'd be surprised if its MySQL interface accepted statement batches. It looks like you would have to break it up into 2 separate queries, without semicolons.
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ALTER world DROP injustice, ADD peace;