You require a clear path to the point of origin for your spells.
Both Thaumaturgy and Minor Illlusion target a point of origin for an area of effect (within your range).
You have to be able to target a specific point which requires a clear path, which you do not have because the wall provides total cover (unless there are holes in that wall or some other way that provides you with a clear path), but you can place the point of origin on your side of the wall:
Targets (PHB 204):
A typical spell requires you to pick one or more targets to be
affected by the spell’s magic. A spell's description tells you whether
the spell targets creatures, objects, or a point of origin for an area
of effect (described below).
A Clear Path to the Target (PHB 204):
To target something, you must have a clear path to it, so it can’t be
behind total cover. If you place an area of effect at a point that you
can’t see and an obstruction, such as a wall, is between you and that
point, the point of origin comes into being on the near side of that