I need to know the name of the tool that can be used to remove the plug on the main sewer drain. The drain is recessed so I cannot use a regular wrench to reach it. The plug has a square nut type of protrusion which I am sure was put there to open the plug with the right tool. I just don't even know where to go to find this tool or what to even ask for.. so the name and most likely place to find one would be helpful.

I need to know the name of the tool that can be used to remove the plug on the main sewer drain. The drain is recessed so I cannot use a regular wrench to reach it. The plug has a square nut type of protrusion which I am sure was put there to open the plug with the right tool. I just don't even know where to go to find this tool or what to even ask for..so the name and most likely place to find one would be helpful.

You have a Brass Recessed Cover Plate. Measure the square hole and ask for square hole lug wrench, **OR**
You can do what we do when we get a pesky cover. Simply take a hammer and chisel,(see image) and start it turning counter clockwise.
**OR**
Take a hammer and beat it out. It can be replaced at most plumbing shops. Good luck, Tom