Hi Pat,
No, if you remove the repeat and re-publish the survey from Connect it will not delete and create a new feature service. Simply the repeat is removed from the survey form, however the related layer still exists in the feature service with the related data and attachments.
Note that moving the image question from the repeat (related layer) to the parent layer will mean the attachments are now being stored against a different layer. If you have existing data and surveys collected already this will mean that attachments for old and new surveys would now be in a different structure and layer. You may want to consider this before making the change, especially if this is on a production survey with already collected production data.
Regards,
Phil.