It would need to be paired with expert diplomacy at a minimum. I can think a few countries with no military Costa Rica and Lichtenstein. Costa Rica defers to allies in time of conflict and Lichtenstein just pays another country for their military.

According to wikipedia most are island nations and get to rely on the ocean and vast distance for safety: https://en.wikipedia.org/wiki/List_of_countries_without_arme...

It doesn't seem like anyone simply cedes territory and gets to stay a country.