If someone deletes the iCloud account, can you still use Find my iPhone?
Find My iPhone is part of the iCloud service therefor it does requires an Apple ID (iCloud account).
If the the Apple ID was deleted Find My iPhone will no longer work until you 'connect' it to another Apple ID.
How To Use Find My iPhone To Get Your Stolen iPhone Back
the find my iphone tracking settings are specific feature of an iCloud account. Without an iCloud account on the device, i think there is no ability to remote track it.
now if someone delete icloud account i think you have to contact apple support.
Maybe with IMEI
iOS: How to find the serial number, IMEI, MEID, CDN, and ICCID number
iCloud: Find My iPhone overview
iCloud: Locate your device
If Find My iPhone can’t locate a device, the last known location is displayed for up to 24 hours.
iCloud: Use Lost Mode