You can delete template versions when they are no longer relevant. And you can delete all template versions for an object type, e.g. Account, if you no longer want to use ARPEDIO Sales for this object type.
Please note, that you cannot get a deleted template version back - there is no way for you to regret deleting a template version. After pressing Delete you will get a pop-up asking whether you are sure; and if you answer Yes to this, then there is no way back.
Sales templates are created per object type. You may have enabled ARPEDIO Sales for several object types: opportunities, accounts, leads and even custom objects. The template versions apply to only one object type - thus deleting template versions for Accounts does not in any way impact in the template versions for Opportunity.
When you delete a template version, then that version will no longer be in the list of template versions. If you delete the published version, then you will not be able to assess that particular object type, e.g opportunity, and you will not get a Sales heatmap for that object type. You would need to publish another version in order to use Sales assessments again.
If you delete all template versions, including the published version, then it would seem that you have not enabled ARPEDIO Sales for that object type, e.g. opportunity. You can create a new template for that object type, and begin all over again with an empty version 1 - or you can import one of the ARPEDIO best-practise templates, and use this as a starting point. However, you cannot build on the template versions you have just deleted.