While you are unable to delete ad campaigns, ad groups or ads within the simulation, you can pause them. Pausing an ad campaign will stop the ad groups and ads associated with it from running in that round.
We do not allow things to be deleted because then there will be no record of all of the ads you have created. The pausing feature will allow you to keep a record of everything you have done. To pause, simply click on the play icon (green triangle) next to the item you want to pause. It will turn into a pause icon when it is paused.
The only thing that can be deleted within the simulation is your keywords from a specific ad group. You can do this by clicking on the keywords tab of the PPC dashboard and then selecting the little box next to the keyword you wish to delete.
Scroll to the top of the table and you should see an actions button. Click on the actions button and then select remove. This will allow keywords to become available to use in other ad groups.
If you have any further questions about this, please reach out to email@example.com who will be able to help you.