prow/github/client.go
func (c *Client) DeleteProjectCard(projectCardID int) error {
	c.log("DeleteProjectCard", projectCardID)
	_, err := c.request(&request{
		method:    http.MethodDelete,
		accept:    "application/vnd.github.symmetra-preview+json", // allow the description field -- https://developer.github.com/changes/2018-02-22-label-description-search-preview/
		path:      fmt.Sprintf("/projects/columns/cards/:%d", projectCardID),
		exitCodes: []int{204},
	}, nil)
	return err
}
func (c *Client) DeleteProjectCard(projectCardID int) error {
	c.log("DeleteProjectCard", projectCardID)
	_, err := c.request(&request{
		method:    http.MethodDelete,
		accept:    "application/vnd.github.symmetra-preview+json", // allow the description field -- https://developer.github.com/changes/2018-02-22-label-description-search-preview/
		path:      fmt.Sprintf("/projects/columns/cards/:%d", projectCardID),
		exitCodes: []int{204},
	}, nil)
	return err
}
// DeleteProjectCard deletes the project card of a specific issue or PR
//
// See https://developer.github.com/v3/projects/cards/#delete-a-project-card