I'm not sure what the current version is called but that's what I play on steam. In the settlement computer interface, in the your office, there should be a button to Abandon Settlement.

I usually just ignore my settlement, it doesn't produce anything useful and because its on a shitty planet that is constantly getting sentinel attacks with storms that make it so you cant see shit. Just makes it a pain

the dumb timmers for building new buildings are way to slow or I would find another one