How do I remove Unifi from my R Pi3?

I got a cloud key and want to get unifi off my pi. How do I do that?

Tried

sudo apt-get –purge remove UNIFI

But it didn't work. It said,

Invalid operation -purge

Tried

apt-get remove unifi

got

E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)

E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?

Thanks