copying zooms from MacBook to portable drive

[Trixien]

I have several Zoom meetings filed in the documents section of my MacBook. When I highlighted JUST these meetings and dragged them to an attached blank portable disk drive, my entire documents section was copied unto the portable disk. If I try to erase the extra files from the portable disk drive by dragging them to the trash, they disappear from my internal hard drive also. What to do???