1) go to this link and download apk, copy to OTG and install on phone, click open after installation.
2) in settings select Usage information under About. will open web browser.
3) Go to retailsamsung.com website, click Galaxy S6 Edge+_Burn-in Updated, then click ap_SamsungRetailMode_Global_Zero2_1.1_v2.0.2_15082 500_M15072700_P15082500_PROD.apk
4) this will be open playstore, then enter your gmail adress as usual… when finished go back to activation screen and press NEXT and ENJOY
P.S: on new phones dont disable Retail mode without removing Google account if you have… because it will not remove Retail Mode and you cant bypass FRP lock with above method because of Retail Mode factory reset protection – Factory Reset greyed out .