This line is probably more than one string. You can set all of them to empty or space in your languages pack, but you have to watch that there are not used in multiple locations, like settings for example.
Note that string are being cached by Moodle, so changing the string may not have immediate effect. Also, the browser's caching may get into the way.
An alternative would be to comment out the line in code that produces this line in the output.