Puede utilizar la línea de comandos en el terminal.
rm -rvf ~/.Trash/*
Para completar las opciones aquí de la rm página de manual:
-f Attempt to remove the files without prompting for confirmation,
regardless of the file's permissions. If the file does not exist,
do not display a diagnostic message or modify the exit status to
reflect an error. The -f option overrides any previous -i
options.
-R[-r] Attempt to remove the file hierarchy rooted in each file argument.
The -R option implies the -d option. If the -i option is speci-
fied, the user is prompted for confirmation before each direc-
tory's contents are processed (as well as before the attempt is
made to remove the directory). If the user does not respond
affirmatively, the file hierarchy rooted in that directory is
skipped.
-v Be verbose when deleting files, showing them as they are removed.