Not a startup disk (CD/DVD)? Your extra installation disks?
You could try a safe boot & try deleting it. An option I can think of is using a utility that makes all the files visible. Then drag & drop one of the .ds store files over to the one you can't delete so it replaces it.

I'm not sure why that file is visible. My 1st thought was it comes from someone elses system. Have you selected it to get info & check permissions of the file. Change the permissions/ownership to "you" & then try deleting it.