Can't delete local files, "Permission Denied"

There are several files on my Mac (OSX 10.9.5) that I can't delete.

I have tried from the GUI and from Terminal, but I always get "Permission Denied":

$ rm -f LigatureSymbols-2.11.eot
rm: LigatureSymbols-2.11.eot: Permission denied

Even with "sudo":

$ sudo rm -f LigatureSymbols-2.11.eot 
Password:
rm: LigatureSymbols-2.11.eot: Permission denied

Here is a directory listing:

-rwxrwxrwx  1 Web  staff    4096 Jun 26  2014 ._LigatureSymbols-2.11.eot
-rwxrwxrwx  1 Web  staff    4096 Jun 26  2014 ._LigatureSymbols-2.11.otf
-rwxrwxrwx  1 Web  staff    4096 Jun 26  2014 ._LigatureSymbols-2.11.svg
-rwxrwxrwx  1 Web  staff    4096 Jun 26  2014 ._LigatureSymbols-2.11.ttf
-rwxrwxrwx  1 Web  staff    4096 Jun 26  2014 ._LigatureSymbols-2.11.woff
-rwxrwxrwx@ 1 Web  staff   83542 Jan 30  2013 LigatureSymbols-2.11.eot
-rwxrwxrwx@ 1 Web  staff   82468 Jan 30  2013 LigatureSymbols-2.11.otf
-rwxrwxrwx@ 1 Web  staff  201950 Jan 30  2013 LigatureSymbols-2.11.svg
-rwxrwxrwx@ 1 Web  staff   83340 Jan 30  2013 LigatureSymbols-2.11.ttf
-rwxrwxrwx@ 1 Web  staff   62636 Jan 30  2013 LigatureSymbols-2.11.woff
drwxrwxrwx  2 Web  staff   16384 Mar  5 08:59 _notes

I am logged in as "Web", so it seems that I am the owner. It also seems that I have full permission (read, write, execute).

I tried looking for flags (such as "immutable") that might prevent deletion, but there don't seem to be any:

$ ls -leO
-rwxrwxrwx@ 1 Web  staff  -  83542 Jan 30  2013 LigatureSymbols-2.11.eot
-rwxrwxrwx@ 1 Web  staff  -  82468 Jan 30  2013 LigatureSymbols-2.11.otf
-rwxrwxrwx@ 1 Web  staff  - 201950 Jan 30  2013 LigatureSymbols-2.11.svg
-rwxrwxrwx@ 1 Web  staff  -  83340 Jan 30  2013 LigatureSymbols-2.11.ttf
-rwxrwxrwx@ 1 Web  staff  -  62636 Jan 30  2013 LigatureSymbols-2.11.woff
drwxrwxrwx  2 Web  staff  -  16384 Mar  5 08:59 _notes

I tried removing the "immutable" flag, even though it doesn't seem to be set, but to no avail:

$ chflags nouchg LigatureSymbols-2.11.eot
$ rm -f LigatureSymbols-2.11.eot
rm: LigatureSymbols-2.11.eot: Permission denied

I notice some "extended attributes" (@) on the files, but nothing that would obviously prevent deletion:

com.apple.ResourceFork     286 
com.apple.quarantine        42 
com.apple.metadata:kMDItemWhereFroms       137

And I can't seem to remove these attributes either:

$ xattr -c LigatureSymbols-2.11.eot
xattr: [Errno 13] Permission denied: 'LigatureSymbols-2.11.eot'

Not even with "sudo":

$ sudo xattr -c LigatureSymbols-2.11.eot
Password:
xattr: [Errno 13] Permission denied: 'LigatureSymbols-2.11.eot'

How can I remove these files from my system?