/Volumes/SearchOffers
means it is a "disk drive" of some kind: either
- a volume on one of your own hard drives, but it could delete that
- A USB fob or similar
- A CD-ROM, DVD etc. This might be a media CD or DVD (music or movie) with additional features. This would be read-only, which would explain why the antivirus can't remove it. If so simply eject it.
- a mounted disk image, which comes out of a disk image file such as .DMG. Many of these are read-only.
You can launch a Finder window, and look along the left edge for a "disk drive" called SearchOffers. It should be readily visible if it is mounted. You can single-click to select it, then hit "Get Info" to determine the source .DMG file if any. Then select File/Eject... And then delete the .DMG.
You can instead launch Disk Utility (Finder, Applications, Utilities) and it will list the volume SearchOffers under whichever disk drive or .DMG it came from. (Assuming you haven't ejected it yet).
Careless behavior in Disk Utility can do a lot of damage to disks other than your boot disk, so be careful and read any "Are you sure?" messages. But it's not nearly as touchy as Terminal.
Given the name, I suspect this is a .DMG file that came bundled with software you obtained from one of the "download software" sites out there. In the future, use preferentially first the Apple App Store, then the software manufacturer's own page (which, granted, can be difficult to identify clearly).