To delete the trash please follow the below steps:
1: Open the Cpanel with the login details you have received on your registered mail,then click on File manager under FILE section.
2: Once you are in file manager in Right top corner there is option of "VIEW TRASH" once you click on it you will see the trash files.
3: You can delete those files by clicking on the EMPTY trash option next to VIEW trash option on right top corner on file manager.
4: Once you clicked on EMPTY trash the files will be removed from the panel permanently.