This is a new capability of the choose-tree feature in tmux 2.8. From tmux(1):

Key Function Enter Choose selected item Up Select previous item Down Select next item x Kill selected item 

So after you've navigated to the right window, press x, then when you are prompted:

Kill window 1?

...press y to accept. This also works for killing individual panes, or even whole sessions.

This is a new capability of the choose-tree feature in tmux 2.8. From tmux(1):

Key Function Enter Choose selected item Up Select previous item Down Select next item x Kill selected item 

So after you've navigated to the right window, press <tmux prefix> + x, then when you are prompted:

Kill window 1?

...press y to accept. This also works for killing individual panes, or even whole sessions.

From the "choose-tree" section of tmux(1):

Key Function Enter Choose selected item Up Select previous item Down Select next item x Kill selected item 

So after you've navigated to the right window, press x, then when you are prompted:

Kill window 1?

...press y to accept. This also works for killing individual panes, or even whole sessions.

This is a new capability of the choose-tree feature in tmux 2.8. From tmux(1):

Key Function Enter Choose selected item Up Select previous item Down Select next item x Kill selected item 

So after you've navigated to the right window, press x, then when you are prompted:

Kill window 1?

...press y to accept. This also works for killing individual panes, or even whole sessions.