Erase and Restore without internet

download your Current operating system from Apple, and create a bootable USB .

This will allow you to initialize the computer and reinstall the MacOS.

hi Alfonso. you may want to add this link to your list of resources:

How to create a bootable installer for macOS – Apple Support

once you have the USB stick, you no longer need the internet to clean install the OS.

Do you have a time machine backup? This process is 100% destructive, and a TimeMachine backup properly stored on an external drive is the only way to recover all your data and apps and whatever you don’t miss now.

1) download Catalina from here https://apps.apple.com/ca/app/macos-catalina/id1466841314?mt=12

2) Rename a USB memory stick 16GB minimum as ‘untitled’

it will be erased by the next process.

3)Open Terminal and enter this command line:

sudo '/Applications/Install macOS Catalina.app/Contents/Resources/createinstallmedia' --volume /Volumes/untitled --nointeraction

4) when done(it will take many minutes to complete), Restart your computer holding the option Key. Select the USB with the fresh OS.

5) Use Disk First Aid to erase and Drive,

6) Use Install MacOs to reinstall Catalina.

After restart your computer will be like brand new, suitable to be given to a new user OR

you can re-enter your Apple ID and select to restore your data from your TimeMachine backup.

One complication: to successfully restore from TimeMachine, your User ID, your Home folder Name and your HardDrive Name, all have to match the existing ones, or the backup may not restore properly.

... Late 2013 ...

It partly depends on the version of macOS you currently have on that machine. I suggest it's better to do the reinstall via Internet Recovery.