Ways to remove creatures with Shroud
Yes, there are. A creature with shroud can't be the target of spells or abilities, but it still can be effected by ones that don't target.

Some examples are ones that destroy all creatures like Wrath of God, deals enough damage to all creatures like Blasphemous Act, or gives all creatures -X/-X like Black Sun's Zenith.

Another common way of dealing with shrouded creatures is by forcing its controller to sacrifice it with something like Diabolic Edict, though this require them to only have one creature, or want to keep their other creatures more than the wall.

You can also remove shroud from the wall either with Arcane Lighthouse or cards that remove all abilities without targeting like Polymorphist's Jest.

You could also give smaller creatures that it blocks deathtouch with something like Coat with Venom.