how do I cancel a service before it is delivered?

how do I cancel a service before it is delivered?

I ordered a gig. A few days later the seller contacted me and said there was a problem with delivering the gig and it would be a few days before he could deliver. After a few days I contacted him and asked about the status of the order. He said he couldn't deliver at this time and I should cancel my order. How do I cancel my order?