Hey there Manish S,
It sounds like you are unable to turn off Find my iPhone in the settings on your iPhone. I would use these steps from the following article about removing your device from Find my iPhone:
iCloud: Remove your device from Find My iPhone
Remove an iOS device or Mac on which you can’t turn off Find My iPhone
If you can’t turn off Find My iPhone on the device, turn off the device so it goes offline, then remove it from Find My iPhone on iCloud.com.Note: If you have an iOS device, you can also remove your device by first erasing it—just follow the instructions below to remove a device you don’t have. You can later restore the device from an iCloud or iTunes backup.
- Turn off the device.
- Sign in to icloud.com/#find on another computer with your Apple ID (the one you use with iCloud).If you’re using another iCloud app, click the app’s name at the top of the iCloud.com window, then click Find My iPhone.
- Click All Devices, select the offline device, then click Remove from Account. If you don’t see Remove from Account, click All Devices again, then click the Delete (x) button next to the device.If the device comes online again, it will reappear in Find My iPhone. To make sure your device doesn’t reappear, turn off Find My iPhone on the device (follow the instructions above to remove an iOS device or Mac), or if you have an iOS device, you can erase it, then remove it (follow the instructions below to remove an iOS device you no longer have).
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