[Eeglablist] removing data from the study datasets

[zahra fotovatnia]

Hello all,
I have been creating a study and I have entered data for 17 participants. It seemed one of the files related to participant 13 had a problem. I cannot add any more files to it because this error pops up " the left and the right sides have a different number of elements.". I used the "clear" button to remove this file from the study but it does not work. I cannot remove this file and continue entering files of other participants. How can I remove one file? 
Thank you Zahra