Moving Folders after import

'm using Thunderbird under Windoze XP SP3

Following recent posts from me about importing from Eudora, imported messages ended up in "local folders" as opposed to being located with the relevant email address - I use three. I have been able to copy two sets of folders to sit with the relevant email address and then deleted the duplicate folders from "local folders"

However the third, the biggest of the three only copies partially - e.g. some folders only, no messages inside - and when I tried to delete all in the new location wanting to start again I cannot delete the folders in the new location

Can the panel advise what I should now do to move the remaining folders from local folders to be associated with the relevant email address? Thanks in advance to all