I created How can I stop YaCy from starting when my machine starts? and was pointed to How to enable or disable services? as a general answer. Unfortunately I voted to close my own question before confirming that the answer did indeed work (it didn't), and it has since been confirmed as a duplicate.
I have updated my original question to reference the general answer, and note how it doesn't apply to this specific service (YaCy search engine). Please reopen the question to allow this non-general case to be addressed. Thanks!
(If I discover a generalisable solution, I will happily update the general answer and vote to close again :D )