You should be able to check your dashboard and yes it is possible to delete
I would tend to prep up a hackster project in WORD or similar until I am ready then just copy/paste as I need and how I need.
Doing it that way I found gave me a better idea for layout in hackster and let me fine tune it with ease and have a full backup copy too.
Sketch I would simply do in either CREATE or the desktop IDE where you can track it a little better.