My grandfather is my guard and he is an American citizen can he legalize me? He pays income taxes. All he wants is legalizate me

Unfortunately, there is no way that your grandfather can obtain legal immigration status for you based on your family relationship. There are only certain categories available for family members, and there is no category that allows a grandparent - even one who is a citizen and pays taxes - to petition for a grandchild. The fact that he needs your assistance does nothing to change this, nor does the fact that he is your guardian.

You don't mention your age, your current immigration status & history, where your parents are/are they living/what is their immigration status, or anything else about your background (education, plans for the future, etc.) You may well have other options, and should speak with an immigration attorney to figure out what might be possible.

Good luck.

When did your grandfather become a US citizen? Did either your mother or father ever live in the US or have green cards? These questions, and others, may determine whether your parents (and perhaps you) have a possible claim to US citizenship by virtue of parentage. And, no, your grandfather can't directly petition for you.

Good luck!