I play an abjuration wizard, and I recently encountered a situation where I wanted to take damage (in order to get a saving throw to permanently end an aboleth's charm effect that was only temporarily suppressed). So, I asked my party to hit me with an attack.

However, I realized that I had my Arcane Ward activated, and the wording of the feature seems to say that it always blocks any incoming damage unconditionally (PHB, p. 115):

Whenever you take damage, the ward takes the damage instead. If this damage reduces the ward to 0 hit points, you take any remaining damage.

I also don't see any language in the ability that would allow me to choose to dismiss the ward.

Luckily, in this case, the attacker was a rogue, and because I was letting him hit me, he got advantage and therefore Sneak Attack, which was enough to punch through the ward and deal a bit of damage to my actual HP with a single attack.

However, this raised the question:

If I actually want to take damage for some reason, is there anything in the Arcane Ward feature that lets me do so without needing to first reduce my ward to 0 HP?

No, they can't, by the rules as written.

As you note, the feature says:

When you cast an abjuration spell of 1st level or higher, you can simultaneously use a strand of the spell’s magic to create a magical ward on yourself that lasts until you finish a long rest. The ward has a hit point maximum equal to twice your wizard level + your Intelligence modifier. Whenever you take damage, the ward takes the damage instead. If this damage reduces the ward to 0 hit points, you take any remaining damage.

While the ward has 0 hit points, it can’t absorb damage, but its magic remains. Whenever you cast an abjuration spell of 1st level or higher, the ward regains a number of hit points equal to twice the level of the spell.

There is no option for you not to benefit from the ward while it has hit points. It simply says that if the ward has hit points and you take damage, the ward takes the damage instead - not that it "can", but rather that it does.

Of course, your DM could reasonably houserule that the ward is under your control, and that you could choose to weaken it, dismiss it entirely, or essentially cause it to "flicker" and temporarily deactivate.