for an entire year my room mate had this shadow on his wall and he never mentioned it to any of us…..
I have a few methods I use depending on how I am feeling. Sometimes I will use a cheese cutter or a wire tool right after throwing the mug but while its still on the wheel head and cut down the side. Other times I will let the cup get leather hard and then I’ll trim it and then cut or carve the sides.
hope that helps