If you're not already familiar with setting up distribution plans, view this support article for more information.
Deleting a distribution plan can be done in two easy steps.
Step 1) Open your list of distribution plans and click delete next to the plan you wish to delete. A confirmation modal is displayed confirming you want to delete the distribution plan.
Video Overview: Here is a video overview walking us through this process and showing you what happens if a distribution is already using a distribution plan and you can't delete or edit.
Have a great day! :)