Hey there, thanks for reaching out. We see you are wondering how to close your tabs. You can do this by hovering the pointer over the top middle of the browser tab and an X should pop up somewhere to close the tabs. This options closes all tabs but one. To close individual tabs, there will be a little X on the corner of the tab that you can click to close the tab.
If you are unable to close your tabs, then you should hold your power button down until it prompts you to shut down or restart the device. Click restart device and there should be no open tabs or you'll be able to close them.
Hope this helps solve your issue!