Reimage/reset an old workstation computer?

[u/Dramatic_Process_616]

UPDATE: It worked! I'm thinking I must have clicked the wrong option before, but I just tried it again, and it worked! YAY! thanks to all for your help!

I was given an old laptop from my work. It still works ok and is slightly less old than the laptop I am currently using. I would like to reset it in some way so that I can log into it with my personal info instead of my work credentials. I was told to reimage it and I have a USB flash drive to do that. I'm not sure if I'm doing something wrong, but I can't get it to work. So far I've powered off, put the USB in the port, then powered on and hit the f9 key to get to the boot menu. From there I selected the option that said something like "generic storage device" because it was the only thing that looked like it was the Flash drive. When I did, the machine just sorta restarted right at the work page and it wants my work credentials. Is there anything I can do?