To delete "old" articles (I assume these are rejected or archived and unpublished articles!), you must log in as Editor.
Then, access the Archive(s?) and delete those you don't want to keep.Check the system's documentation
for more info on roles and how to add roles to a registered user...
Through the Files Browser you'll only delete the files themselves, leaving database records.
Doing that will create a mess in your database references.
I HIGHLY RECOMMEND YOU NOT TO DO THIS!!
Ramón Martins Sodoma da Fonseca
Analista em C&T
Coordenação de Tecnologias de Informação
Instituto Brasileiro de Informação em Ciência e Tecnologia - IBICT
Ministério da Ciência e Tecnologia - MCT