Trojan virus warning in safari wonT allow normal operation even after closing safari and restarting

If this is on a computer, you may  have adware/malware installed. Try downloading this program which was written by Thomas R, a long time poster. The program will search for malware/adware. The program will do the work for you which makes it easy. It may be necessary to run more than one scan. After running the scans, restart the computer.

Malwarebytes Anti-Malware for Mac      10.10 and later.       

Web site for download   https://www.malwarebytes.com