Done all steps suggested within How to completely remove Thunderbird? and still end locating:
locate -e thunderbird
/usr/share/app-install/desktop/thunderbird:thunderbird.desktop
/usr/share/app-install/icons/thunderbird.png
/usr/share/icons/HighContrast/scalable/apps-extra/thunderbird-icon.svg
/var/cache/apt/archives/thunderbird-gnome-support_1%3a45.5.1+build1-0ubuntu0.16.04.1_amd64.deb
/var/cache/apt/archives/thunderbird-locale-de_1%3a45.5.1+build1-0ubuntu0.16.04.1_amd64.deb
/var/cache/apt/archives/thunderbird-locale-en-gb_1%3a45.5.1+build1-0ubuntu0.16.04.1_all.deb
/var/cache/apt/archives/thunderbird-locale-en-us_1%3a45.5.1+build1-0ubuntu0.16.04.1_all.deb
/var/cache/apt/archives/thunderbird-locale-en_1%3a45.5.1+build1-0ubuntu0.16.04.1_amd64.deb
/var/cache/apt/archives/thunderbird-locale-hr_1%3a45.5.1+build1-0ubuntu0.16.04.1_amd64.deb
/var/cache/apt/archives/thunderbird-locale-sr_1%3a45.5.1+build1-0ubuntu0.16.04.1_amd64.deb
/var/cache/apt/archives/thunderbird_1%3a45.5.1+build1-0ubuntu0.16.04.1_amd64.deb
/var/lib/app-info/icons/ubuntu-xenial-main/64x64/thunderbird_thunderbird.png
Is it safe to remove these files manually in the event you actually want to do fresh install of Thunderbird afterwards? This is my last attempt to get Thunderbird to work on my Ubuntu driven system since one of the mail boxes simply doesn't pull new messages using IMAP protocol no matter what I did in settings.
~/.thunderbird
, where all your mail boxes & data are stored. Probably the most (and only) relevant one in case of unfixable errors.