Unpin FTP folder from Windows 10 Quick Access

I didn't find a user friendly way either.

Anyway, the pinned folders are stored in:
%APPDATA%\Microsoft\Windows\Recent\AutomaticDestinations

I.e. typically in
C:\Users\username\AppData\Roaming\Microsoft\Windows\Recent\AutomaticDestinations

Just delete the files from there.

I can't comment because of reputation but I'd like to point out that Martin answer is also helpful if you move your Download folder to other location. I moved mine from C:\User\Name\Download to D:\Download but Quick Link stuck at the first one and couldn't be unpinned.

The solution was to:

1. Press Win+R
2. Paste %APPDATA%\Microsoft\Windows\Recent\AutomaticDestinations and press Enter
3. At this point you can delete everything in there (there should be only a bunch of files with .automaticDestinations-ms extension) or - if you want to delete only one - open them in Notepad; the file is mostly-giberish but it also shows path.

I found an easier way to do it: we get the greyed "Expand" context menu only for FTP links. If, in the Quick Access folder, we multi-select (holding the Ctrl button) the FTP link(s) plus another normal one, then the normal context menu is displayed and we can unpin them all at once.