A file attached to a comment can't be deleted from the Attachments panel. (The Delete File option will appear unavailable for that file.) The only way to delete a file attached to a comment is to delete it from the comment itself, or delete the comment that the file is attached to.
To quickly visit the comment from the Attachments panel, click the word “comment” under the filename.
Delete a file attachment from the comment panel
- Click the More Options icon to the right of the comment.
- Select Edit comment.
If Edit comment is grayed out, it's likely that you don't have the correct permissions to delete the attachment. You will need to contact the person who left the comment and ask them to delete the attachment, or reach out to the Owner or an Admin on the sheet to have them delete the comment where the file is attached.
- Hover over the attachment you'd like to delete and click the trash icon.
The file should now be removed from the comment and the sheet.