The other day I had this file (-rw-r--r--) created under strange and unknown circumstances. If you treat it as "normal" file, you will get error messages.
There are many ways to deal with such files/directories but the quickest way is to give the full path or the path from the current location. In other words, to put /full/path/ or ./ in front of it:

shell@gz:~$ ls -la
total 0
drwxr-xr-x    2 root     system         4096 Nov 03 09:00 .
drwxr-xr-x    4 root     system          256 Jul 19 14:04 ..
-rw-r--r---    1 root     system            0 Nov 02 16:30 -rw-r--r--

Fail:

shell@gz:~$ rm -f '-rw-r--r--'
rm: Not a recognized flag: w
Usage: rm [-firRe] [--] File...
shell@gz:~$ ls -la "-rw-r--r--"
ls: Not a recognized flag: w
ls: Not a recognized flag: -
ls: Not a recognized flag: -
ls: Not a recognized flag: -
ls: Not a recognized flag: -
ls: Not a recognized flag: -
Usage: ls [-1ACFHLNRSabcdefgiklmnopqrstuxEUX] [File...]

Success:

shell@gz:~$  ls -la ./-rw-r--r--
-rw-r--r--    1 root     system            0 Nov 02 16:30 ./-rw-r--r--
shell@gz:~$ rm ./-rw-r--r--
shell@gz:~$ ls -la ./-rw-r--r--
ls: 0653-341 The file ./-rw-r--r-- does not exist.