When you use the "/bind <key> <command>" format, you only put the "/" on the /bind part. The / tells it to execute the bind command. So by putting a / in front of the skipcutscene, you are telling the ui to execute /skipcutscene when you should be telling it to execute skipcutscene. So the proper format should be (remove quotes if typed in directly) "/bind delete skipcutscene" without a / attached to skipcutscene.
However, while that is proper syntax, I have bound the command and tried it and it did nothing for a warp in or warp out.