Cut it into small pieces with heavy-duty metal snips or aviation shears
Score it deeply with a metal file or grinder, then bend and break it
Drill multiple holes through the card to disable it
Use a hacksaw to saw it into several sections
Crush it in a vise or with a hydraulic press until it is deformed beyond use
Shred it with a metal-capable industrial shredder
Return it to the issuer’s metal card recycling or destruction program if available