Should I sell my S&P 500??

Lately I've been questioning if I should sell my S&P 500, but all of it. I've been recently having a conversation recently with a friend, and they were basically asking me why I have holdings in both S&P 500 and the FTSE All World. And to be honest, my response was a bit emotional one, which was I've had my S&P 500 literally since I started investing. Like I'm emotionally attached to this, and I'm scared to sell it. Which I know isn't right and if you're emotionally attached to something, it's therefore not an investment. And he basically went on to tell me that the FTSE All World is 60% of the S&P 500 anyway. So by being invested in the S&P and the All World, there's just major overlap and it's just very unnecessary. In fact, am I putting more risk literally the S&P 500, or am I actually have better global diversification if I'm in the FTSE All World, but still getting advantages of the S&P 500? Me is think. Should I stay invested with the S&P 500, or should I sell that and go all in on the FTSE All World? Let me know.