Canceling a DBA
Depending on the state (and in most cases - county) you can either cancel the DBA, or just let it expire if cancelation is not crucial. To better answer your question I would need to know the state and county where you have registered this DBA.
Keep in mind that the DBA is not a separate entity but just an alias to your actual entity (be it an LLC or corporation, or sole proprietorship/partnership). This means that even if you cancel the DBA you might still be liable for whatever have happened (or is happening) with the business.
If the DBA belonged to an organized entity (LLC, Corporation etc) then in order to properly end the business you should dissolve the company. If its a general partnership I recommend you to consult a business attorney on the proper ways to end a general partnership in your state.