Hey, not to sure how to do this. So lets say an AI forward pushes a colony on you. The planets are terrible, so I want to get rid of him but I dont want to inhabit the planets or colonize. Is the only option to kill, and raze? Its super bugging that taking territory from someone can lead you to just a terrible colony or terrible approval..

Right now I want to invade the AI next to me, but for each colony I take im either gonna destroy my approval or max my threshold of colonies with colonies and planets that do not benefit me in any way?

Razing planets ant the penalty incurred in doing so are temporary. Unless of course you're in a Dictatorship or Autocracy since the penalties are waived/ignored. So while the approval hit in razing can hurt, its temporary and not permanent like occupation can be with over-colonization. If Benthic Gems spawned in your universe and you're lucky enough to occupy planets that have them, then you might be tempted to go on an occupation spree since Benthic Gems can cut the penalty in half or outright eliminate it if used twice. Granted by the time you eliminate the penalty you can raise your colonization cap through a system improvement(so... its kind of a wasted luxury???).

Build 'Evacuate system'. This will give you a free colonization ship and some dust.