I work as a security guard for this office lease building with a bunch of different companies in it. One of the companies threw out a bunch of computers, keyboards etc so I managed to grab 3 " dell optiplex 7460 all in one" computers, power cable, mouse and keyboard. Ideally I'd like to keep on for myself and sell the other 2 after getting into the computer itself but as you can imagine they're all still password protected from the old employees using them. Top of the screen upon booting says access to this system is for authorized personnel only. Has the company name. Asks for a user name and password. Any ideas on what I can do with these or how to maybe do a factory reset of some kind?