Hi, thanks for using JustAnswer.com I am Cris and will be glad to assist you with your question. On your iPhone do the following:
Go to "Settings"
Scroll down to "Safari" and tap on it.
Scroll down to "History and Website Data" and tap on it clear the history and data.
Then re-open Safari and see if now the message is gone.
Let me know the outcome. If this resolves your issue please rate my service and the top and submit. If not reply back to me to further troubleshoot.