Maximize current window
From Vim Tips Wiki
created 2005 · complexity basic · author Narayanan Iyer · version 5.7
Map a key to make the current window as large as possible (without closing other windows):
map <F5> <C-W>_<C-W><Bar>
If you don't mind closing other windows, you can make the current window even larger:
Or you can use CTRL-W o (or CTRL-W CTRL-O), which does the same thing as
:only in even fewer keystrokes.