I think you might have placed them there at somepoint, or saved them there. There's no way the mesh would've landed in your objects folder without you placing them there~
If you don't want them, then just remove them from your objects folder :)
However, I am sure you would be permitted to use them as you have gotten them somehow in a download. If no one wanted you to use them, I'm positive they wouldn't place them in a download people are able to access.