Usermod -l

https://linux.die.net/man/8/usermod

sudo usermod -l newusername oldusername

--login NEW_LOGIN The name of the user will be changed from LOGIN to NEW_LOGIN. Nothing else is changed. In particular, the user's home directory name should probably be changed manually to reflect the new login name.

See also

• sudo, id, visudo, useradd, userdel, usermod, groups, passwd, chown, chmod, chgrp, groupadd, groupdel, Passwordless sudo, passwd (package), sudo --help