The OEM auxiliary electric fan moves considerably LESS air than the stock mechanical fan. By removing the stock primary fan and subsituting another OEM electric fan, you will be reducing the airflow through your radiator.
I've seen numerous posts by people who have tried this -- except most use aftermarket electric fans that flow better than the OEM, which was after all designed and intended only as an auxiliary fan and not as a primary. I'd estimate (from meory) that probably 40% felt they had as good or better cooling than the OEM setup, and the other 60% found they had made the problem worse instead of better.
Those figures might be off, could be 50/50. But those were mostly using electric fans that push more air than what you're describing.