I'm in a WhatsApp group and the topics discussed there are more of vulgarity. I need to delete that group. Please help.
You can leave this group only, you can't delete it for everyone.
Go to the Group -> Group Info.
On the very bottom of the user list, you can see the button Delete and exit group
You will exit this group and the group will be deleted on your phone.
You won't recieve new messages (as you're no longer in the group) and the messages you already have will be removed.