Removing a file is an operation on the directory, so the directory permissions are what matters. If you have write permission in the directory, you can remove any file**. Write permission for the file is not required, but if you try to remove a file for which you do not have write permission, the rm
command will, in the absence of the "-f" flag and if stdin is connected to a terminal, ask for confirmation before doing the removal. But that is really just a warning, and you do
have the permission needed to remove the file.
**Directories with the "sticky" bit set in their permissions ("t" in the last character of the ASCII permissions) have an additional restriction. To remove a file from such a directory you must be the owner of the file or the owner of the directory. This bit is commonly set on publicly writeable directories like /tmp (perms "rwxrwxrwt").