Under section 3.5 of the Mozilla foundation Bylaws [1], Baker could be removed by the board, which consists of Mitchell Baker, Brian Behlendorf, Helen Turvey, Nicole Wong, Amy Keating, and Mark Surman [2]. Note that the directors are elected by the directors in the first place so sadly, it is unlikely to happen.

[1]: https://static.mozilla.com/foundation/documents/mf-bylaws.pd...

[2]: https://foundation.mozilla.org/en/who-we-are/leadership/