Mod security minimum configuration HOW

How to set mod security for minimum protection?

What are must have and what are OK to let it go?

You can choose which rules to enable or disable by your own depending on software you have installed to achieve optimal protection level.

Yes I know I can do that but why should I disable the rule itself? I want just the rule does not apply to me but if I disable the rule it will disable it on the server will it not make the server less secure?