Change user name
usermod -l newname oldname
Change group name
groupmod -n newgroup oldgroup
Change home directory name
vipw
Modify home directory name and then
cd /home
mv oldname newname
usermod -l newname oldname
Change group name
groupmod -n newgroup oldgroup
Change home directory name
vipw
Modify home directory name and then
cd /home
mv oldname newname