You can withdraw a request by marking it as solved. The request must be assigned to an agent before you can mark it as solved.
Click your profile icon in the upper-right side of any page, and then clickMy activities.
Click the title of an open request to open it.
Select the option on the lower side of the request to mark it as solved.
The request must be assigned to an agent. Otherwise, you do not have the option to mark it as solved.
Enter any comment you want in the reply and click Add Reply.