I came across the phrase 心配いりません and from what I understand it means "Dont worry". It is formed by using the する-verb 心配 (worry) and いる (to be needed). What I don't understand is why there is no particle or something between 心配 and いる.
Does this mean that する-verbs don't necessarily require the verb する or one of its related forms? Or am I just overthinking it and a particle just being omitted?
心配いりません is the same as 心配はいりません (literally "worry is not needed"), but は is omitted. Here 心配 is a simple noun meaning "worry" or "anxiety". Suru-verbs are essentially nouns followed by する ("to do"), so you can treat words like 心配, 運転 ("driving"), 勉強 ("studying") also as simple nouns.
Since 心配いりません is something people say very often, you can safely omit は even in formal settings. Another similar set phrase is 問題ありません ("No problem"), which is a short version of 問題はありません. Just like English speakers don't usually bother to say "There is no problem", this は is usually omitted for brevity, too.
