If so which cards should be removed? If not a good option what else is good?
If you look at
Lost Legacy you'll see that you can only target non-artefact spells, which won't do much about a Mardu Vehicles like Ladof mentioned. Not just because of
Heart of Kiran and
Aethersphere Harvester are artefacts, but because of the reoccurring threats,
Unlicensed Disintegration only needs an artefact as well as
Toolcraft Exemplar and
Inventor's Apprentice, so if you take away one, another one exists to take its place, and all you've done is delayed the player, temporarily.
I don't believe that
Lost Legacy would be that useful for the Saheeli combo, you can use it only on turn 3, which is when Saheeli comes into play, assuming you've
gone first. Then you have turn 4 to cast it to either remove
Felidar Guardian or Saheeli, assuming that neither are on the field. The best defence against that deck would be to sideboard
Authority of the Consuls into your main deck, because
Felidar Guardian would come into play tapped, thus circumventing the combo.