Coming Back to Leviathans

[Greenskyguy]

It's been a while since I had a serious game of Stellaris going and with Leviathans, it's really been a change. Not entirely I understand everything about Worms and the thing with Messenger Race really messed up my Earthling population I can't purge. So if anyone has any advice to remove Squid-Humanoids, that'd be great.

 

[Jerev]

It's been a while since I had a serious game of Stellaris going and with Leviathans, it's really been a change. Not entirely I understand everything about Worms and the thing with Messenger Race really messed up my Earthling population I can't purge. So if anyone has any advice to remove Squid-Humanoids, that'd be great.

What you talk about is not a Leviathan feature but the Horizon Signal event chain. Aside from purging I don't know any easy way available pre 1.5 patch to get rid of another race. Do you even have pops of your starting race left?
You could van migration, resettle all squids on one planet and release it or gift it to another empire.