I understand what you are asking, but why do you want the information completely separated like that? Thunderbird is more than capable of having multiple mail accounts in a single profile. I have 18 or so mail accounts in a single profile and I have heard of some that have a hundred of more that they monitor from a single profile in Thunderbird.

Thunderbird can also have more than one profile, so you could selectively choose which account you wanted open without physically deleting anything.

In answer to your original question.

1. Press the windows key + R
2. type %appdata% and press entry in the run dialog that opened.
3. Delete the Thunderbird folder shown in the windows file manger that opened from the last step.

Thank you for your help I know it would be easier to just add the new email to the existing ones but I really need the just the new email on the second laptop with out my existing ones. I followed your instruction above to delete Thuderbird and it did deleted. Then I opened Thunderbird again and everything was still there.

What did I do wrong. Look forward to your help got it to work IT WORKED THANK YOU HEAPS

Oh dear I have pressed windows and the + key and the R key and my screen has gone huge What do I do help ALL FIXED