Hard reset

[Nootaku]

Hello,

I bought my phone 2 or 3 years ago, but back then it didn't really work out for me.
I want to try again since the software has been updated.

Problem is I really don't remember my password.

So it's impossible to sudo or root.

Which I why I would like to format the phone and do a factory reset.

Any idea how this can be done ?
I could not find it in the documentation.

Thanks in advance.