USB port connecting internal hard drive. Is it what is happening here?

Hi everyone. Please help me with this question if you can. I bought a new PC a couple of days ago. The system unit was embled by the seller using components of his choice (I don’t know much about PC). So I trusted him. Now the strange thing happened: there is an icon appearing on the lower right hand corner of my screen right next to the time display. The icon is the same as when I connect a USB flash stick to the PC. So I am thinking that this icon should not be appearing now since I don’t have any USB device connected to the PC now. When I hover my mouse above the icon it says “Safely Remove Hardware”, and when I left click the icon, it says “Safely remove Hitachi HDS721616PLA380 - Drives(F:, E:, D:, C:)”. And this is my hard drive, which I think should be an internal hard drive. The property tab says that its location is: Location 0 (Primary ATA Channel). But why is this icon appearing? Please help. Thank you everyone.