Restore the device as new, then restoring from a backup, but only do this after you’ve made a backup of everything on your iPhone 5s.
# Connect the iPhone to a computer and launch iTunes
# From iTunes, choose to “Back Up Now” – this will make a most recent backup of the iPhone and everything on it (you can also backup to iCloud if you want) – wait for this to finish
# When the backup is complete, choose to “Restore iPhone” from the iTunes options
# Let the restore process complete, when finished the iPhone will start as if it was brand new. In this setup process, choose to restore from your backup that you just made.
Note that restoring the iPhone this way will also install the latest version of iOS available for your device.