Certified GKH Gardening Expert
Be sparing. Gingko have adapted to be slow growing, and don't heal well from intentional damage. They are very strong trees, and don't get heavily damaged in nature very often.
You should only go about this while it is dormant. This will be when sap content is low, and will give the tree its best chance to heal over while in Winter.
This article will give you more information on the general care of Gingko Trees: https://www.gardeningknowhow.com/ornamental/trees/ginkgo/ginkgo-tree-care.htm