Presumably you are not able to find the file by name and then delete it ?

First of all make sure you know where any other downloads are, moving them if necessary. Then try clearing the download list. If that does not work then reset the downloads folder by using about:config

For instructions have a look at

• What to do if you can't download or save files

the clear list button does not remove...how do I re-set download folder using about:config?

Do you want to remove the file from the download manager window or from the hard drive?

Did you try to highlight that entry and press the Delete key?

If the file listed in History > Show All History > Downloads ?

If you can't remove the file in the download manager widow then try to delete the downloads.sqlite file in the Firefox Profile Folder

• http://kb.mozillazine.org/Unable_to_save_or_download_files

I want to remove from both the download file and hard drive. The delete key does not work when I highlight the item and clearing the history file does not clear the item.

Did you read the linked articles ?

• https://support.mozilla.org/en-US/kb/cant-download-or-save-files
• http://kb.mozillazine.org/Unable_to_save_or_download_files

and maybe any related articles linked from them.

What suggestions have you tried so far ?

Possibly the file is already deleted, and the problem is with the download manager trying to keep track of it. Have you tried

1. setting the downloads to use a different folder for the saved files,
2. then tried downloading the file again to the new location ?
   • Does that work to get the download ?