Once you've created a training plan, you are the "owner" of that plan. If you allow it, other people can use your plan and create their own version of it, but they will never be able to change your original plan. This also means that only the owner of a plan is able to delete a plan.
You can easily spot if you are the owner of a plan by checking the following two things. When you are the owner you will see:
1. "delete this plan" at the bottom left of your screen.
2. "save as new plan" at the bottom right of your screen is accessible.
This means that if you don't have the delete option or the "save as new plan" box is ticked and cannot be unticked, you are not the owner.
It could happen that you have a certain club plan in your system that you want to alter or delete and it's not yours. A club plan can only be created by employees from your club, so it shouldn't be too hard to locate the owner of the plan. Just log in through his account, and you will have the option to delete or edit the original plan.