Right click on tab
Right-click one of the tabs. There are several ways to close the tabs. To close only the selected tab, use the function "Close tab". However, you could also simply click on the cross in the top right-hand corner of the tab.
Further functions are "Close All Others", "Close Unmodified" and "Close All".
Close all tabs
The possibility to close all tabs at once can also be found in the left sidebar.