Yubel?

What happens when i have to yubel-Terror incarnate on the field do they destroy their selves or do they stay on the field because its effect?

Yubel Terror Incarnate destroy all other monsters on the field ( except itself ).

They would destroy each other.
Terror Incarnate's effect is "During your End Phase, destroy all other monsters on the field." If it had said "Destroy all monster's on the field except 'Yubel - Terror Incarnate", then they would be safe, but in this case, they'd both be destroyed, since Terror Incarnate destroys all monsters on the field except that card.

~Aster Phoenix