It depends on whether you are using vi(
set -o vi) or emacs(
set -o emacs) editing mode within your shell.
By default, your shell generally defaults to emacs editing mode.
In emacs mode, deleting to the end of the line can be accomplished by using the command ctrl-k.
If, however, you happen to be using vi editing mode in your command shell, the same result can be accomplished by typing Esc(which will place you in command mode) followed by d-$(if you want to delete the entire line, enter dd).
If you are uncertain as to which editing mode that you are currently using in your shell, enter the command
set -o from the command line and you will be able to determine which editing mode that you are currently using:
To switch your command-line editing mode, simply type either:
set -o vi
set -o emacs