Some scores trapped in pdf converter

Hello,

I tried to convert some pdf files some days ago and some of them are trapped in the import web page. https://musescore.com/import
Now I'm not able to import another pdf file and I don't know how can I remove this trapped files in order to clean my import page. Is it possible to clear the queue in the import web page?

Thank you very much in advance for your help!

Marta.