Good afternoon.

I can't join on my computer... I mean, not even in the windows, so I only can go to BIOS booting mode.
So I need to format my laptop, but has an admin password to boot from my Pen.
I searched a lot to solve my problem but I can't go any further.
Can you help me ?
Laptop: Dell Latitude 5420 model P137G i5.
Service Tag: H6YNNQ3
Thanks in advance.