Dell Printer 5350dn hard reset.

Hello guys, I am new at the community and I thought one of you could give me a hand and this issue. I just bought a couple used Dell Printers specifically Dell 5350dn. The problem I found is that they have passwords and I can't get access to the printer menu making impossible to use all the future and power these printers have.  I would like to know if one of you have the idea how can I reset the printers to factory reset to start the printers as new. I already did my research and read the manuals but I did not find anything useful that can resolve the problem. I would really appreciate your help.

Thanks