Do you have the Thunderbird folder from old PC or just the profile? That is important to give proper instructions. If old PC is available, that would be a plus. For full cleaning, uninstall thunderbird and delete the c:\users\<yourid>\appdata\roaming\thunderbird folder. Do likewise for c:\users\<yourid>\appdata\local\thunderbird. With these gone, there are no remnants left of old accounts. Here are proper steps:

Here is the link for moving a profile in Windows when installed in default location:

https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer

here is the info in brief steps:

1. ensure thunderbird is NOT running on old machine
2. enter %appdata% in search window on task bar and press Enter key
3. this should open windows file explorer in Appdata\roaming folder
4. highlight the Thunderbird folder and copy to external media
5. ensure thunderbird is installed on second computer and NOT running
6. enter %appdata% in search window on task bar and press Enter key
7. you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This may prompt to overwrite an existing folder of same name. allow it
8. start thunderbird and all should be there

I do still have Thunderbird untouched on the old computer. Initially I had installed Thunderbird on the new one, set up accounts and used it for a few days then tried to do the file transfer but none of the "old" info showed up. Then I read it should be a clean install, close it right after it's installed then go through the transferring steps. I have deleted Thunderbird and the files you listed (I didn't realize there were 2). I've used the file explorer to look for anything related to Thunderbird. I even emptied the recycle bin and restarted after everything was deleted. Downloaded and installed Thunderbird, expecting it to be clean but all the information from the newer info I setup still remains! Am I still missing something?