If memory serves me well. the MF135 like its predecessor had just the one lift lever. And if I remember, if you had a tipper cart connected, the cart never started to lift until the draught arm had risen to as high as they could go before oil started to go to the lift ram on the cart. If that is the case, then when the arms are lifted, full oil pressure will at the same time be trying to go through the auxiliary oil pipe. Again to answer your question, I see no reason the pipe could not be removed, as long as it is capped or plugged to take full hydraulic oil pressure. Saying all of this, is the fact there is a pipe there such a problem and might it at a later date be useful.
