If you want to scrap your package draft and start over, you can delete your draft:
Open your Asset Store Publisher Portal page and select the All Packages in the left navigation bar.
Click Draft in the status bar.
A list of your draft packages appears.
Click the pencil-shaped edit button next to the name of the draft you want to delete.
The Edit package page appears. This displays your package’s details.
Click the Delete button in the top right corner of the page.
In the pop-up dialog, click Delete to confirm the deletion, or click Cancel to keep the draft.