Despite what you might read, yes you can take the colour out of a meerschaum pipe. I know this because I have done it to mine when it wasn't colouring the way I wanted it to. Did it twice, in fact.
If you have a gas stove, hold the meerschaum above the flame, quite low to it, and the heat will begin to expel the oils (and colour) pretty quickly. Use an old cloth and occasionally wipe it to expedite the process.
It happens quickly. I noticed that when the pipe cooled again, the colour turned further white again. It probably won't ever become pure white, but mine got damn close.
Also, the colouring in my pipe was quite heavy after about a year or so of continuous use. Turned just about as white as a new golf ball.
Good luck.
Note: My pipe was supposedly "high grade", and almost certainly block meerschaum. Maybe pressed will explode in your face, who knows.