I purchased a gig but it is for the wrong amount , How do cancel it and start again
Be kind to the seller and request a mutual cancellation. When you cancel an order on your end, it creates a pretty strong negative rating for the seller. As long as you state that you ordered the wrong amount for a gig and request a mutual cancellation, customer support will have your back and make sure you get a refund. Plus, a mutual cancellation doesn’t negatively affect the seller, which makes the seller very, very happy.
Also take note that if you overpaid and you cancel to buy less, the balance of your overpayment cannot go back to your bank. The balance will still need to be used on Fiverr. If you don’t think you’ll need other gigs soon you might want to talk to the seller before cancelling. They might be able to provide something extra to make it worth your overpayment. If you did underpay @bachas85 has the best suggestion and you wouldn’t need to cancel.