Yes you do. Unless you have an upper that doesn’t have a forward assist, your upper has worn pin holes, a proprietary barrel nut due to an aftermarket handguard, or a bent pin then you cannot take the pin out without removing the barrel nut(thus the barrel). Any milspec upper the pin will not clear the forward assist when pushing back(after you remove the forward micro circlip) without force that would either scratch the shit out of the upper or bend the hinge pin.
Some billet upper you can get them to clear, especially ones like the vltor modulars. Some barrel nuts will have tapers/shapes/cuts that allow the pin to slip by after the handguard is removed. On a milspec rifle though, the stock M16/M4 type barrel nut won’t let the pin pass by.
it’s all designed that way to capture the pin in the event that the circlip were to pop off and the pin to vibrate loose.