On the default Gnome desktop, a menu button with the app name and icon appears in the top bar next to the activity whenever the app window has focus.
Previously, there was an option to disable the Gnome Tweaks feature. However, starting with Ubuntu 19.10, this option is no longer available.
If the app menu doesn’t help, you can remove it on Ubuntu 20.04 / Ubuntu 20.10 via the Gnome Shell Extension.
1.) First open a terminal (Ctrl + Alt + T) and run the command to install the chrome-gnome-shell package. This will add a Gnome Shell extension for your web browser (if you don’t have one).
sudo apt install chrome-gnome-shell
2.) Next Go to the extension web page, Turn on the toggle icon to install.
Do you see the toggle icon? Follow the link to install the browser extension and refresh the web page.
After installing the extension, you need to disable the app menu.
Also, if you want to remove the “Activity” button on the upper left, please install it. This extension In a web browser.