Why can't I delete my files?

I copied some files from a data DVD to my ext4 /home, and all of the files are read only.

This is what all the files are like:

emma@emma-W54-55SU1-SUW:~$ stat Drivers/Drivers_List.rtf
  File: ‘cd/Drivers/Drivers_List.rtf’
  Size: 28120       Blocks: 56         IO Block: 4096   regular file
Device: 801h/2049d  Inode: 656521      Links: 1
Access: (0400/-r--------)  Uid: ( 1000/    emma)   Gid: ( 1000/    emma)
Access: 2014-01-17 05:34:46.000000000 +0000
Modify: 2014-01-17 05:34:46.000000000 +0000
Change: 2015-02-01 23:11:04.226865424 +0000
 Birth: -

When I try to delete them, I get 'Permission is denied', even though I'm the owner. Changing the mode to 660 doesn't work either. The only things that work are changing the mode to 777 or deleting them as root, using sudo.

I thought only an i attribute made files unable to be deleted by their owner, so what's going on?