If you would like to edit a template that is available within the "Add Slide" modal, like the screen below:
You will want to complete the following steps:
Create a new report (most likely a non-filterable slide deck)
Click add slide then apply the template you want to edit
You will need to go to the first slide and delete it, as it is likely blank
Save the slide deck as a new template
At this point you have the new version save and the old version is still available, so you will want to delete the old version if you no longer need it.
To delete the template you will need to have the VC Admin role. Then follow these steps:
Go to the admin panel
Click on templates
Find the template you no longer want to have available and click the trash can icon
