Wulf hope you can help me. I am admin on my server, normally 2 groups admin and default but I accidently created a new parent group using the cammand -

oxide.group parent admin default or maybe the other way round

oxide.group parent default admin. The situation I now have is 
3 groups - Normal group admin, admin parent group default, and finally 
normal group default. So I am admin in the default group and perms
are all incorrect. Please help me remove the parent group default
and get the server running normally again. Look forward to hearing
from you with the correct commands, many thanks, regards, JackDaw

Have you tried /chat group list , (to see what groups you have)
Then /chat group remove <groupname> (the one you dont want)

oxide.group parent admin ""

All players will be in the default group, regardless of this parent being set or not; just keep that in mind.

Entered the command and hey presto! problem solved, can't thank you enough, really appreciate your quick reply, many thanks, JackDaw