There are a lot of posts on this and multiple ways to do it, but not much that is 100% "out of the box"

The ideal approach depends on the conditions for when you want the button be hidden or disabled.

For example, you can:

• Prevent the submit button from working if fields don't pass validation
• Use custom JavaScript to show/hide the button
• Use a custom HTML button and show/hide with Field Rules

Hide submit button based on other fields - Laserfiche Answers