People talk about equity release as if it is money in their hand, money to spend as they wish.
Equity release is another word for debt - a secured loan, a remortgage -set against the equity in the house. It has to be paid back in the same way as another mortgage or secured loan, with interest.
If you are elderly, it is possible to release equity for a monthly income or a lump sum. When you die, or sell the house, all the monies plus interest (if not paid back on a monthly basis) is repaid to the equity company.
So, as already pointed out, the only way to use the equity and pay off your mortgage is to sell the property.