denite seems to use the cmdline like ctrlp instead of a buffer like Unite. Is there a way to edit your query with normal mode commands?
C-o to jump to normal mode. This mode works in two ways: you can navigate the candidates buffer and you can issue some normal mode commands to modify your query.
You won't have a cursor when it's at the end and some commands don't work as expected (you can't
dw to remove a word), but a bunch of functionality is there. It's always going to be a bit weird since the inputs are doing two things at once (should
e to move to the end of a word or edit the selected file?).
You can customize the mode switching mapping like this:
" Switch modes with C-l (like esc but won't quit) call denite#custom#map( \ 'normal', \ '<C-l>', \ '<denite:enter_mode:insert>', \ 'noremap' \) call denite#custom#map( \ 'insert', \ '<C-l>', \ '<denite:enter_mode:normal>', \ 'noremap' \)