[root@renwole.com ~]# mongo
MongoDB shell version v4.4.0
connecting to: mongodb://127.0.0.1:27017/"id" : UUID("1ea1-4343-9523-167a101973a9") }
MongoDB server version: 4.4.0
> use admin
> db.auth("admin","InaM6Aip#2JBlWwY")
1
> show dbs
admin  0.000GB
config  0.000GB
local  0.000GB

> use renwoledb
> db.createUser(
  {
   user:"renwole",
   pwd:"renwolecom",
   roles:[{role:"dbOwner",db:"renwoledb"}]
  }
)

MongoDB shell version v4.4.0
connecting to: mongodb://127.0.0.1:27017/"id" : UUID("7be9-4c30-ad2e-2a5b58127ab7") }
MongoDB server version: 4.4.0
> use renwoledb
switched to db renwoledb
> db.createUser(
   {
    user:"renwole",
    pwd:"renwolecom",
    roles:[{role:"dbOwner",db:"renwoledb"}]
   }
 )
uncaught exception: Error: couldn't add user: command createUser requires authentication :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
DB.prototype.createUser@src/mongo/shell/db.js:1343:11
@(shell):1:1

> use admin
switched to db admin
> db.auth("root","renwolecompassword")
1
> use renwoledb
switched to db renwoledb
> db.createUser(
   {
    user:"renwole",
    pwd:"renwolecom",
    roles:[{role:"dbOwner",db:"renwoledb"}]
   }
 )
Successfully added user: {
	"user" : "renwole",
	"roles" : [
		{
			"role" : "dbOwner",
			"db" : "renwoledb"
		}
	]
}

> use admin
> db.createUser({user: "root",pwd: "renwolecom",roles: [ { role: "root", db: "admin" } ]})

> use renwoledb
> db.changeUserPassword("renwole", "renwolecompwdnew")
> db.auth("renwole","renwolecompwdnew")
1

> db.system.users.remove({user:"renwole"});
WriteResult({ "nRemoved" : 1 })

> db.system.users.remove({})

> use renwoledb
switched to db renwoledb
> db.dropDatabase()
{ "ok" : 1 }
>