Explain how water, through the processes of weathering, erosion, and deposition, can both create and destroy Earth s landforms?

It's not easy to explain it all in a few words. Further nobody would want to write a full essay here on the subject.

But let's consider a river. The source would be from a mountain range. As it flows down huge rocks and boulders are carried along down stream. Due to friction the rocks erode and become smaller. By the time it these reach the lower plain or a sea, these rocks become sand.

In the lower plain area the river erodes its banks and often changes course. The old courses are left behind in the form of lakes. These lakes are 'C' shaped and called lagoons. The river deposits the silts when it reaches the sea or ocean (we call it mouth of the river). The alluvial deposits form into land masses at the mouth of the river to form deltas.

Weathering can be a chemical or physical process and generally refers to the gradual breakdown of rock.The main result of this that we see is the presence of soil. Soil is made of the broken down minerals and particles of rocks and organic matter.
Erosion refers mostly to the removal and transportation of material this is mostly done through running water; rivers, strems, the sea etc.
Deposition is where all this eroded stuff ends up and encompasses things like how deposited materials form layers based on density. Hope that helps a little.

Watering can break down rock and erode it. A lot of water at one time can break down rock so much that it causes a lake eventually. And this is probably your homework, so you can go off of that :)