Hi @Kyle Zhan
Database mirroring must be removed before you drop the database
Typically, it indicates that the database you're trying to delete is still in a mirrored state.
Also, when I delete the mirror on Principal DB, the status of Mirror DB should change to "Restoring..." instead of becoming Disconnected/In Recovery.
Normally, after removing mirroring on the Principal DB, the Mirror DB should move to Restoring state. Then you would be able to drop the database without encountering the error.
Best regards,
Cosmog
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