Wacatac (also known as Trojan:Win32/Wacatac) is a trojan-type infection that stealthily infiltrates computers and performs a number of malicious actions. Cyber criminals typically proliferate this malware using spam email campaigns and fake software 'cracks'.
Windows Defender would mention the potential threat to you but it is up to you to delete it altogether from the system. Currently, if the Virus is in the Quarantine and you can delete it from there.