'Remove SSP projection vector.
Note: The projection vector can only be removed if it is inactive
(has not been applied to the data).
Parameters
idx : int | list of int | str
Index of the projector to remove. Can also be "all" (default)
to remove all projectors.
Returns
self : instance of Raw | Epochs | Evoked'

def del_proj(self, idx='all'):

    if (isinstance(idx, string_types) and (idx == 'all')):
        idx = list(range(len(self.info['projs'])))
    idx = np.atleast_1d(np.array(idx, int)).ravel()
    if any((self.info['projs'][ii]['active'] for ii in idx)):
        raise ValueError('Cannot    remove    projectors    that    have    already    been    applied')
    self.info['projs'] = [p for (pi, p) in enumerate(self.info['projs']) if (pi not in idx)]
    return self
