Safari: Open the tab switcher, then tap and hold Done, and choose Close All Tabs
Safari: Open the tab switcher, then tap Close All (if shown)
Chrome: Open the tab switcher, then tap Clear Browsing Data or Close All Tabs (if available)
Chrome: Long-press a tab, then choose Close All Tabs (if available)
Firefox: Open the tab switcher, then choose Close All Tabs (if available)
Firefox: Long-press a tab, then choose Close All Tabs (if available)
Other browsers: Open the tab switcher, then use the Close All Tabs option if available