removing rally point ability

[storyyeller]

How do I change a building so that the Set Rally Point icon doesn't show up in the abilities box but the player can still change the rally point by right clicking on the ground and the building can still train units?

[Arabidnun]

Impossible I believe, as Set rally point is an ability, without it you will have to create some sort of extravagant trigger which would be......worthless?