Managing Templates

Currently, no. You can manipulate the database directly in the sheetnode_template table :-) I'll keep this as a feature request.

Here's a quick-and-dirty patch that will at least let you delete templates.

Moving to D7 for fixing.

Any solution yet for drupal 7?

Possibly it may be better if sheetnode templates were created as entities? Or if there were some way to manage and update the sheetnode templates after they have been created?

I am currently thinking that the managing of Templates is one of the key concerns for moving Sheetnode forward. Whether we could have an interface like Paragraphs. This would require Entity API, but would be a massive benefit to anyone who is using the templating system inside Sheetnode. I am adding this to my plan for a 2.x release - https://www.drupal.org/node/2633426