I need to turn off the lost mode

Read about how to use Lost Mode in Find Devices on iCloud.com

Use Lost Mode in Find Devices on iCloud.com - Apple Support

When you find your lost device, do either of the following to turn off Lost Mode:

- You can turn off Lost Mode by entering your passcode on the device.

- In Find Devices on iCloud.com, click All Devices, then select the device that’s in Lost Mode.