Always remove other snippet confirm modes when deleting snippets

## Description
There was an issue with the marionette snippet object that would not replace the confirm mode on a snippet that has been selected for deletion. This will remove that error by removing the marionette variable that was supposed to track confirmation mode.

This will resolve #31.

### Testing Considerations
* [ ] Ensure snippet delete works
* [ ] Ensure snippet confirm mode toggle works
* [ ] Ensure snippet confirm mode is removed when confirming another snippet