Sure, here is a step-by-step guide on how to conduct a literature review on the assessment of cholera prevention among the residents of Yemetu Oja Metropolis in Oyo State:

1. Identify Your Research Question: Your research question is already defined - "What is the assessment of cholera prevention among the residents of Yemetu Oja Metropolis in Oyo State?"

2. Search for Relevant Literature: Use academic databases like PubMed, Google Scholar, JSTOR, etc. to find articles, journals, books, and other scholarly works related to cholera prevention, its assessment, and specifically any works related to Yemetu Oja Metropolis in Oyo State.

3. Evaluate and Select Articles: Not all articles you find will be relevant. Read the abstracts, conclusions, and skim through the content to select the most pertinent ones.

4. Categorize Your Selected Articles: Group the articles based on sub-topics, methodologies, conclusions, etc. This will help you when you start writing the review.

5. Analyze and Interpret: For each article, identify the key findings, the methodology used, and the relevance to your research question.

6. Synthesize the Literature: This is where you start writing the review. Summarize the key findings from each source and how they relate to your research question.

7. Write the Review: Start with an introduction that outlines your research question and the purpose of the review. Then, present the findings from the literature in a logical and coherent manner. Finally, conclude by summarizing the key findings and identifying gaps in the literature that your research will aim to fill.

8. Revise and Edit: Review your work, check for any errors, and make sure your arguments are clear and logical.

Remember, a literature review is not just a summary of articles. It's a critical discussion where you identify relationships, contradictions, gaps, and inconsistencies in the literature, and suggest the next step for future research.