[ESS] comint-delete-output including prompt

[Richard M. Heiberger]

You didn't specify, so I assume you are talking about ess-transcript-mode
used for myfile.rt and myfile.st, the recommended file extensions for the
output from S and R.

Put the cursor at the beginning of the line containing the command.
C-@                        ;; mark position
M-x comint-next-prompt     ;; go to next prompt
left-arrow twice           ;; beginning of line
C-w                        ;; kill region

Rich