Hello viragoo,
Thank you for posting in the Apple Support Communities. We'll provide you with the best options.
When you tap the alert, does it give you the option to view it on the map, play a sound, or learn more about the item? Check out the section "Use item safety alerts" in the user guide below to learn more:
View details about an unknown item in Find My on iPhone
If you're still unable to disable it because your iPhone can't connect to the server, taking these steps often help resolve issues of connecting to Apple services and servers:
If you can't connect to the App Store, iTunes Store, or other Apple services
If this concern isn't resolved after taking the steps above, we recommend that you contact Apple Support directly. Depending on your region, you may be able to reach them here:
Get Support
We hope this information is useful. Kind regards.