Can I disinherit my children in my will?

Technically yes, you can disinherit your children, but here's the important part: in most autonomous communities there's the "legitimate share," which is a portion of your estate that by law belongs to them even if you want to prevent it. What very few people mention is that if the reason is that they want to punish you or you have conflicts, often it's worth more to make a will that simply ignores that relationship (without mentioning explicit disinheritance) because trying to formally disinherit them can generate long and costly lawsuits that the heirs end up winning anyway. Consult with a lawyer, but also present this strategy to them: sometimes the cleanest thing is not to put dynamite in the document.

It's not as simple as just crossing their names off your will, because even though you have the right to decide what happens to your assets, the law requires you to leave them a minimum share (the legally reserved portion). But here's the detail most people don't mention: you can disinherit them conditionally, meaning you can set out in your will the specific reasons why you're disinheriting them (like serious ingratitude or abandonment), and that gives you more legal backing if someone challenges it later. Best thing is to talk to a lawyer who specializes in this because depending on your autonomous community, the percentages for the legally reserved portion vary quite a bit, and you'll have a written record of your reasons in the notarized document.