Cannot delete files on Terra Station SMB share that I just created

[ImaginaryTango]

I have a Terra Station and have several SMB shares on it. I have one that I'm accessing from several Macs in my LAN. On one Mac, I unzipped a file, which created a new subdirectory and put all the unpacked files into it. Now that I've accessed what I need, I cannot delete some of the files from the Mac where I created them - they're apparently in use and there's a lock on them. This happened within 5 minutes after I created the files by unzipping. Now I can't delete those files at all. I went to the web control panel and I see where I can manage my shares, but I can't see any way, from within the web control app, to get to individual files or directories. (And I can't find a way to set up ssh so I can just connect from the terminal and do the same thing.)

Without restarting, having to do a lot of reconnecting, and so on, how can I delete these files?