Here is a screenshot from Native Access
It depends on whether you have sessions/projects using Kontakt 6 or not:
If you do, you should keep it installed as Kontakt 7 will not automatically replace Kontakt 6 content in your DAW projects. (Note that Cubase, Nuendo, MASCHINE and KOMPLETE KONTROL work a little different as noted here.)
If you don't, feel free to uninstall it.
