There is no one-click remove feature in any software. Try to make sure your source is in MP3, it works best this way. And be aware that you can never completely eliminate the vocals. The maximum you can do is push it down real low, but you will always be able to hear a slight remnant/artifact of the vocal track, reducing it any further will most probably damage track fidelity and it just wont sound right. What you want to do is split the left and right channels using Audition or SoundForge into separate files and then open the files in multi-track editing mode. Once you've done that, use the program's polarity reverse feature on the left channel and then use apply a low end shelf cut starting at 200Hz. Then merge the tracks in stereo mode (make sure you merge or mix, dont overwrite) and then save the file. Just so you're wondering, all these processes are non-destructive so you can fiddle with it to your heart's content, adjusting the dB levels and the EQ before you're satisfied.
Its been a long time since I worked with SF, so I cant give you the exact steps and what buttons to click. But you can find these options easily in the software's menus.