It is better to just apply a matte black vinyl rectangle over them. Did so for my Mustang. The ST labels don't bother me as much, so I am putting them off for now.
The Mustang forum has some threads about grief for those trying to remove them. They are stuck on hard. Penalties include leftover gummy residue, permanently wrinkled visor material, and permanently discolored visor material for those that tried to clean off the gummy residue.