As already mentioned, the suction foot can be removed. I wash the Zyliss by hand and make sure that the cavity under the foot does not fill up. After drying, leave the appliance in a non-suctioned state. This also allows any moisture to escape from the cavity to prevent mould.
By the way, mould can be removed well and effectively with vinegar water.

You can remove the suction plate, which you can also buy individually as a spare part in specialist shops. I replaced mine a few years ago after the grater no longer held. However, I cannot say whether this is necessary for cleaning in your case.