E[Sn²] = (n-1/n)sigma²

This is biased variance. So to get unbiased variance, we take E[(Sn-1)²] which according to videos is = sigma²

how is this equal to sigma²? How did we claim that this is indeed equal to sigma²?

Instead of giving the answer directly, can you just tell me how to proceed with equating E[(Sn-1)²] = sigma²

Because if I’m not wrong, if we were to replace n with n-1 in the E[Sn²] formula, we should have ended up on just sigma², but we don’t. So I’m stuck. Help me please

Thanks in advance