How would you hide, clean and decorate this?

power washer to clean it. What about hofstra plant or Carex Buchananii (type of grass plant)

You could try to pressure wash the brick if that bother you. For the garden, add some fresh soil and plant mini bushes or plants. No room to add soil, then dig out some first. Day lilies, for instance, will grow just about anywhere in any kind of condition.

Power wash- the walls and remove some of the soil. Fill area with gravel- large stones- and put arrangement of planters on the gravel and maybe a couple of solar powered lights. - maybe intersperse small planters on the ledge under the windows to add some fun hanging plants and character. Make sure all plants are low maintenance. Come winter you could put cut branches from evergreens or even artificial plants . I could see small artificial Christmas trees.

Follow above instructions to clean the brick. Clean up debris from soil, loosen it with a soil fork or trowel, etc., and plant hardy sedum ground cover. There are several varieties, and once established, are very drought tolerant. If you plant groupings of three or four varieties, the result will be colorful greens, and when they bloom, yellows and/or pinks! They get thick enough to discourage weeds, too. I love my sedums.

If you get the western sun, please be aware you best water the first year you put your plants in. I think evergreens are best as they will be an all winter plant. The best thing is to go to a good nursery and chat with them. You might want to dig up some of your soil and augment it with some hollytone ospoma fertilizer. You won't get spashing if you put down a good bark or shredded mulch after planting. Please don't use weed block as the plants will grow and won't be able to get through the weed block. Here in Virginia boxwoods are nice but I don't know about your area. Also hawthorns work nicely.

In no time you will have a beautiful accent to your home.