How can I remove a virus/malware?

Someone used my computer and downloaded a virus that closes out my chrome browser, and tries to install something. I believe it's called "Billboardnet" and "apprc" and "com. macme..." and "MacMechanic", I'm not sure if "com.apple.TCC" is a virus but it won't allow me to open it so I moved it to the trash. Is there any way I can get these files deleted? Every time I move them to the trash and empty it, it always tells me they they're in use at the moment. Thank you!