Hi @Maugusto, welcome to our forum!
Your question has been translated to English as this is an International forum.
If you want to format your device, I would recommend that you perform a software repair using Xperia Companion. This will delete all data stored on the internal storage of your device and reinstall the latest available software. Since data is being deleted, creating a backup using Xperia Companion before you start with the repair is advised!
Let me know if that helps! 
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