The following procedure can be used to delete all user groups using CLI (Command Line Interface).
NOTE:
1. Make sure to export settings before any changes. How to Download Tech Support Files (TSR, EXP, Logs) From Dell SonicWall UTM Firewalls
2.The procedure will remove all user groups.
3. XXXXXXXXXXXX is your 12 digits Serial Number.
admin@XXXXXXXXXXXX> config
config(XXXXXXXXXXXX)# user local
(config-user-local)# no groups
(config-user-local)# exit
config(XXXXXXXXXXXX)# commit