This Telegram app just installs a
.desktop file, its icon and a folder where it saves its data:
Remove the folder with the Telegram and Updater file.
rm -Rf \ ~/.local/share/icons/telegram.png \ ~/.local/share/applications/telegramdesktop.desktop \ ~/.local/share/TelegramDesktop
Note:I installed Telegram by double clicking the Telegram file.
No, you didn’t install Telegram by double clicking, neither
apt was involved in any way. The
tar.xz package contains a pre-compiled executable for Telegram Desktop and it executes it every time you launch it. Simply delete the extracted folder to get rid of Telegram.