TSP or Krud Kutter.
I use vinegar and warm water together and wipe it with a soft rag.
Hi Julia. Begin by mixing one cup of vinegar and two cups of warm water. Be sure that the water is warm. It will cut the grease better than cool water. If you have a heavy build up of grease, add a teaspoon of Dawn dish soap. Wash the wall with a clean cloth. Then use a dry cloth to dry the wall. Good luck Julia.
For small stains, mix: 1/4 teaspoon of soap in a cup of warm water, and wipe. Rinse with clean water, and blot until dry. Clean stubborn grease stains with solution of 1/3 cup of white household vinegar with 2/3 cup of water.
Hi Julia: Dampen a clean, dry cloth with undiluted white vinegar, and wipe down greasy wall. Rinse your cloth with warm water, wring out most of the moisture, and use it to rinse the wall. Dry the damp surfaces with a paper towel, but note any still-sticky spots that need a do-over. Good luck.
Hi Julia, here's a great video to show you how