After you remove the sealants from the package, the 4G box is no longer dangerous. Unless the inner packagings have been damaged and the sealant had contaminated either the inner packagings and/or the outer packaging, the empty box remains not contaminated and therefore not dangerous.
You can ship the empty 4G as non dangerous. You will remove all the Mar ings and labels. DGR 126.96.36.199 refers to single packagings that have been in direct contact with the dangerous substance and/or inner and outer packagings of a combination packaging which had been contaminated by direct contact with the dangerous substance.