Indeed, BASS_ChannelRemoveDSP/FX are just for removing effects that were enabled via BASS_ChannelSetDSP/FX. BASS doesn't have any control over specific Android effects, but you could try disabling audio session creation (which disables effects) via the BASS_CONFIG_ANDROID_SESSIONID option:
BASS.BASS_SetConfig(BASS.BASS_CONFIG_ANDROID_SESSIONID, -1); // no audio session
But note this currently only affects playback, not recording.