Close current pane
panes
// what it does
Ctrl+b x kills the active pane (kill-pane) and hands its space back to the remaining panes. By default it shows a confirm-before prompt — "kill-pane N? (y/n)" — so a stray x won't destroy your work. If it's the only pane in the window, the window closes too.
// shortcut
Ctrl + bx
// gotcha
Killing the last pane of the last window ends the whole session. The confirmation prompt can be disabled, so a rebound x may kill instantly without asking.