Hi Flavio,
There is no need to remove the commands/configs for a group. You can add new HLS streams to a group at any time. For example:
createHLSStream localstreamnames=test1,test2 groupname=myGroup bla bla
will be equivalent to:
createHLSStream localstreamnames=test1 groupname=myGroup bla bla
createHLSStream localstreamnames=test2 groupname=myGroup bla bla
Bryan