Can you install faux log siding over metal siding ?

In general, yes. As long as the metal siding is not rusted or not sealed. However, your best bet is to check with both manufacturers (metal siding and log siding) to get their opinion.

I would remove the metal siding. Any moisture can get trapped behind the wood siding rusting out the metal, damage the sheathing underneath and damage the wood siding.

I’m going with both William and Jeremy, remove it would be your best option. You should be able to sell the metal siding or sell it to the metal recycle place. Chat with the manufacturer of the faux log siding or just look up their installation recommendations. Follow those so you have the warranty.