Simply add these two lines of codes into ~/.vimrc:
nmap <F1> :echo<CR>
imap <F1> <C-o>:echo<CR>
Note: if you using GNOME, then F1 is snatched by GNOME before vim, in which case you will likely get some help menu even if you have disabled F1 from vim. IN this case, simply disable F1 from the terminal --> preferences --> shortcuts --> help --> backspace.