Most electric motorcycle conversions retain the gas tank, but with the bottom cut out. This preserves the style of the bike and creates a place where components can be housed and protected from the elements.
I cut out the bottom of my tank because I thought I might use the space. However, the toolboxes proved much more convenient for mounting components, so the tank did not get used in the end.
First, I drained the gas and left the fill port open for days to allow any remaining gas to evaporate. A friend told me of his cousin who cut into a gas tank without completely eliminating the gas and fumes inside, and lived the rest of his life as a vegetable after the explosion. Not wanting to take any chances, I flushed the tank with soapy water and rinsed it thoroughly.
I had not yet discovered the joys of the angle grinder with metal cutting wheel, so I used other tools: First the sabre saw with metal blade, then hacksaw, then Dremel with a reinforced cutting wheel.
After removing the metal tank bottom, I filed around the tank cut-out with a hand file to remove the sharp edges.
Next: Choose the Components