Hi (& Welcome to OpenStreetMap),

If you want to make the road two-way, you need to cut it at the two nodes (x or the scissors tool if you right click on the relevant selected node in the editor). The existing way then gets split into 3 and you can unset the oneway setting on the bit in the middle. (if you look at a road with a bridge the same principle applies so there are lots of examples)

HTH,

Jerry aka SK53