Remove Simplenews Newsletters?
Inorder to remove Simple newsletter completely. You need to disable and uninstall the module.

Follow the steps


Go to Modules list (admin/modules) and uncheck simplenews letter to disable and click 'Save Configuration' to disable the module
Then Go to admin/modules/uninstall page and select/check the simplenews letter module and click 'Uninstall' to remove all data related to Simplenews letter module from your instance.