Re: Undeletable file

Select the file and hit Command-i.

At the bottom of the inspection window there is an area called "Sharing and Permissions." See if you can unlock that area and alter some of the settings in your favor.

Another solution I've had work in the past is to change the extention of the file name. Add a ".txt" or ".zip" to the end of the file. Sometimes that shakes things up and lets you erase it.