Some websites have this huge sign-up form suddenly pop up blocking the page and there is "X" where I can close it. After I refreshed, the huge pop-up appears. Is there I can disable it without having to sign up?
I did a little research and it appears there's really nothing you can do about this. The opt in forms being used are designed to not be affected by popup blockers and essentially be unblockable.
There nothing you can do with it. There is program or codes that the admin put to there site. That is not a ads so you can't use Block ads extension.
Good news! Today I found a blog post which shows that the huge popup without close button can be closed. Read the post over at: http://malaysiannews.info/2014/09/how-to-remove-pop-up-without-close-cross-button.html