My daughter recently totaled my 1995 SL500 and I'm holding onto the salvage and working on getting it back on the road.

There is a tank inside the front passenger side fender right below the wiper-washer tank and she broke off the front tab so I'm guessing I need to replace that tank but I don't know what it is. I tried searching here and on google and I'm at a loss on this one...

vacuum reservoir for the a/c actuators possibly

This is the tank that I'm talking about. It looks like it is just receiving any fluid the escapes from the coolant expansion tank under the hood and that the car doesn't do anything with this fluid afterwards.

If so can I just remove this tank and let any runoff drip to the ground?

That's the coolant overflow tank. It stores coolant. When coolant gets hot it expands and if the expansion tank can't contain the coolant it will flow to that overflow tank. When the coolant cools down it will flow back to the expansion tank then to the radiator.

If you remove that overflow tank excess hot coolant will flow to the ground. And when it cools down no coolant will return to the expansion tank/radiator because it was thrown out of the system. As a result, you may need to constantly add coolant to maintain the correct level.