What Pantaclica said originally, learn to mute the string when you pull off the 7.
You could use your fretting hand and mute the string with the tip of the finger hitting the 5th fret on the string below the one you are pulling off on.
Or you could palm mute it very carefully with the picking hand just after hitting the note.
Another technique for muting that works well is a slight palm mute, or a sort of hovering over the strings with your picking hand. It manages to keep the strings from ringing unncessarily when you are playing the high ones or sweeping or whatever.
Hope that helps any.