I am trying to process the ITS data but with Itexpress tutorial I was getting some error at taxonomy assignment so I am trying to process it with without trimming by using this tutorial.
But the read quality look very poor, could you please advise how should I process this data.
The error you described in this topic has nothing to do with itsxpress, and everything to do with the taxonomy files that you are using. So you will run into that error even if you trim with cutadapt instead.
Your read quality looks fine to me. Proceed as usual with selecting appropriate parameters.