Sudo

• include your user in the sudo group

#su -
usermod -aG sudo ralph

• list the groups

# groups pi
pi adm dialout cdrom sudo audio video plugdev games users input netdev gpio i2c spi

• remove sudo (or unwanted groups) by not listing after usermod -G

usermod -G pi,video,plugdev,users,input,netdev,gpio,i2c,spi,adm,dialout,audio pi

• check

# groups pi
pi adm dialout cdrom audio video plugdev games users input netdev gpio i2c spi

hardening

On the raspberry pi sudoers are added to the /etc/sudoers.d and must be deleted along with 010_pi_nopasswd file

delgroup pi sudo
rm /etc/sudoers.d/010_pi_nopasswd
rm /etc/sudoers.d/pi