Is there any way to put a skill that decreases money?

YanFly's Skill Core allows you to set such thing
But I lack the experience in Javascripting.
Is there any way that I could do it without having to touch the coding?

have the skill call a common event, and that common event decreases money.
Problem: that will happen after skill execution, and if there is not enough money the skill will still execute before the common event.

but that is the only way to do that without javascript

Decrease money held by the party or decrease the rate at which they accrue money?

This should, in theory, work:

Have your character perform the skill which runs a common event as well as does (null) or 0 damage to an Enemy Target.

Within that common event, use a variable call for the amount of money the player has. If the variable checks out to the amount of gold needed, then use the "Force Action" button within the battle event page to force your character to use said skill against the "last target." Alternatively, you can Force Action to just use the skill on a random enemy, or you can define it using even more variables (but I would not recommend this, it may get quite convoluted and lead to unwanted skill use/skill use to the wrong enemy.)

There are a million ways to skin a cat. Be wary of anybody who states that there is "only one way to do" something.

You could have an event run at the start of battle to check if player has sufficient gold, then disable the skill if they don't. Run that same check if the skill is used after gold was decreased via the skill activated common event.

Yanflys skill core page actually has exact examples of this scenario :) you should check it out and try it.

Or just add $gameParty._gold -= 500; at the front of the damage formula.