Cross out step 2,3,4 in checkout??

when customers check out, they have to click submit each step below:

Step 1: Checkout Options

Step 2: Billing Details

Step 3: Delivery Details

Step 4: Delivery Method

Step 5: Payment Method

Step 6: Confirm Order

At present, i don't need to use the steps 2,3,4 at my website. I want the customer to go from step 1->5->6. How can i do with opencart?

Many thanks!

Phuong Tran