I removed the “axes parameter” for 3 axes in the Font’s custom parameters but somehow they are still available in the master’s widow.
If there is no Axis parameter, Glyphs looks at the values that are stored in the master and adds default axis if any master has a none default value. For the first two axis the default is 100, for all following it is 0 (that is for historical reasons).
Closing and reopening seems to do the trick. However I was surprised to find old axes reappear even thought I had removed them a while ago and had already restarted Glyphs etc.
Thanks!