Using a HELOC to pay off a mortgage can free up cash and potentially reduce interest costs if rates are lower than your current mortgage. It requires good credit, sufficient home equity, and a low debt-to-income ratio. HELOCs offer flexibility but have variable rates and risks like foreclosure if unpaid. Alternatives include making extra payments, home equity loans, refinancing, or reverse mortgages for seniors. Evaluate costs, risks, and goals before deciding.