Deleting users in linux

root@pop-os:/# userdel -rf stark
userdel: stark mail spool (/var/mail/stark) not found
root@pop-os:/# userdel -rf lannister
userdel: lannister mail spool (/var/mail/lannister) not found
root@pop-os:/# userdel -rf kit
userdel: kit mail spool (/var/mail/kit) not found
root@pop-os:/# userdel -rf nicky
userdel: nicky mail spool (/var/mail/nicky) not found
root@pop-os:/# su stark
su: user stark does not exist or the user entry does not contain all
the required fields
root@pop-os:/# su lannister
su: user lannister does not exist or the user entry does not contain
all the required fields
root@pop-os:/# su kit
su: user kit does not exist or the user entry does not contain all
the required fields
root@pop-os:/# su nicky
su: user nicky does not exist or the user entry does not contain all
the required fields
root@pop-os:/# groupdel acme-manager
root@pop-os:/# groupdel acme-employee
root@pop-os:/# groupdel acme-all
root@pop-os:/# getent group | grep -i "acme-manager"
root@pop-os:/# getent group | grep -i "acme-employee"
root@pop-os:/# getent group | grep -i "acme-all"