Uninstalling via FTP might be not a good idea for your WP installation. WP has been built to NOT have to use FTP again. Why forcing people going back to FTP when going back to FTP takes longer than a couple of clicks ? Plus, WP uses to put entries in the database about installed plugins. Removing files and not the DB entries of the plugin itself might be harmful for the WP installation.
Thank you, Jan, for the info. I indeed checked on Firefox and i found the plugin (while it still doesn’t appear in Chrome) and i could uninstall it properly.
It is clearly a glitch affecting the plugin on Google Chrome installations. (else, it would appear like in Firefox.