trim.seq_demultiplexed data_ how to generate group file?


I have to trim primers from my sequences so I am using trim.seq command line. But I got my sequences without barcodes so I can not make a group file. It seems that this is not a problem at this step.
But my next step is to screen maximum and minimum length sequences and, screen.seqs step needs a group file. Please give suggestion, what should I do ?

Looking forward,

A group file is not required to run screen.seqs.

Thank you Dr. Schloss