Colony NPC Problem

I've been building a colony and discovered that an NPC is staying in my colony even though it doesn't have a house (colony deed). I don't know if this is a bug or if it's intentional but either way its kind of annoying me.

 

If you have done some quests to having NPCs join, that is why.
Other means is usually a merchant that has residence, or you built on pre-existing settlement that had a non-hostile NPC.

If you don't want extras coming to colony, don't accept the find a friend; which are usually escort quests. To get rid of such then just lure an enemy towards the NPC or make a clever lava trap to drop said NPC into it. Once that NPC dies it will not return.

I personally don't mind the extras, as it bring more life into the towns/villages that one creates, beyond deed functions...

 

Thanks to these lingering "extras", I filled half a Glitch Fortress with Florans by getting carried away doing quest chains...and I didn't even have any colonists at the fortress itself. It was funny and neat until the lag sent me into permanent bullet time whenever I approached the fortress.