Removing SMScontactsbackup folder
Super Backup and Restore application creates a folder named SMScontactsbackup on internal storage. The application is used to backup and restore contacts, call logs, sms, apps etc. 
Each items are kept in separate folders.
The app also saves  each  app's previous apk's which are updated through play store.
You can delete this folder by these methods.


By removing Super Backup and Restore application from your device, it will also ask permission whether to delete folder and it's contents.
Using any file manager app (here Samsung file manager for Samsung devices),you can delete that folder from internal storage. (N.B if Super Backup and Restore application is not removed, then folder will be created again ).



Note: You need to make sure that, you've restored everything before removing app/ deleting folder.