A word of caution: “the w in bw does not stand for write but for wipeout!”
More from manuals:
:bd
Unload buffer [N] (default: current
buffer) and delete it from
the buffer list. If the buffer was changed, this fails,
unless when [!] is specified, in which case changes are
lost.
The file remains unaffected.
If you know what you’re doing, you can also use :bw
:bw
Like |:bdelete|, but really delete the
buffer.