Can't delete word in front of score

I am using Musescore Version 1, Revision 3996. From when I first downloaded Version 1, in creating a score, a line of music would start off with the word "Piano" in front of it (see example attached) and I am unable to delete it. I used to be able to click on it, it would turn blue, and press delete. Now, when I click on it, nothing happens and I can't delete it. Any ideas?
Bill