How to add “x” close button into upper right corner of Surbma Popup Plugin?

How to add “x” close button into upper right corner of Surbma Popup Plugin? https://wordpress.org/plugins/surbma-yes-no-popup/ uk-text-small{font-size:11px;line-height:16px}.uk-text-large{font-size:18px;line-height:24px;font-weight:400}.uk-text-bold{font-weight:700}.uk-text-muted{color:#999!important}.uk-text-primary{color:#2d7091!important}.uk-text-success{color:#659f13!important}.uk-text-warning{color:#e28327!important}.uk-text-danger{color:#d85030!important}.uk-text-contrast{color:#fff!important}.uk- Read more here:: How…