how to reset user manager

hellow every body
i have a question and need to answer
how can i reset my user manager to its defult position .i mean every think in my user manager
like users/ accounts/ etc. to its original mode

need your replay…

Uninstall the UM package and reboot, then install it again and reboot a second time.

thank you very much.
actually i do what you say immediatlly .

but indeed the login name dose not come back to its original ( admin )

ruther than the password is still as i did it at the last time i made it ( befor uninstall)

thank you again