

You could buy some acrylic markers and try baking the vessel with the new marks for an hour at 375 F.
You might want to work your way up to the temp over a few hours to prevent shattering.
Also, you could put the glass on a sheet and cover with a mixing bowl up keep the heat more consistent.
I say 375 due to temperature discrepancies in ovens and temperature swings.
The glass could still break, but if you are throwing it away anyway, what does it matter?
Ok, my wife uses it during the winter pretty regularly.
Over the summer it is used occasionally, mostly for pancakes or things.
It might actually get used a few dozen times annually, but it is also 20 years old. We usually run it through the dishwasher, so I can’t account for the difference there. Maybe your water is different from ours!