remove Customized by BoldThemes

Hi,

It depends on which theme are you using Bold Page Builder. In Twenty Seventeen theme label “Customized by BoldThemes” is located in Widgets – Footer 2 area.
Otherwise, if you are using Twenty Sixteen, than please use the following statements and add them to Custom CSS field on Appearance > Customize > Additional CSS panel:

.bt-footer-info {
    display: none !important;
}