Open Question: How to remove irrelevant jobs from your resume and also justify the gaps in employment as a result?

My friend has 12 years of total work experience. 6 years in forex trading and 6 years in supply chain. Now she wishes to go back to forex trading. In looking for opportunities, how should she frame her resume? Should she only show first 6 years of "relevant" experience? Wont this make the potential employers wonder, what did she do in the remaining 6 years?