For edit multiple lines, click CTRL+V for init block selection. Click J or K for select the lines, or use arrows up/down.

Now with lines selected, press SHIFT+I for insert on all lines, or SHIFT+A for insert on the end of all lines.

ref: https://vimtricks.com/p/edit-multiple-lines-at-once-in-vim/

You can disable cmp with inline Lua command, invoked by :lua command.

:lua require('cmp').setup({ enabled = false })