How to change the throttle output from aux3 to another aux?

According to quad delta platform, aux 3 is used for connecting throttle. how can i change it from this to another aux ch?

You would need to change the mixer

I see but how to define the output channel.

See In each output channel, the mixer file should declare

O: <-ve scale> <+ve scale>
S: <-ve scale> <+ve scale>

Count the number of M: and Z: defined so far.

If you need to pad it (skipping Aux 3 for example), simply define a NULL mixer using