i started my gladiolas to early in my house and its to cold to put them out yet but they are very big now,can i cut them down a bit or will that hurt them
No you should not cut them back.
If you started them in containers and are going to leave them in them, then just move them outdoors.
Gladiola will not do well moving from container to the ground. They should be direct planting after danger of frost in your area.