You can remove the "Powered by Shopify" link from your footer by editing your theme code, finding the Sections folder, opening footer.liquid and deleting this line, around line 73.

<p class="footer__small-text">{{ powered_by_link }}</p>

Starting Expanse 5.0.0, Fetch 2.0.0 and Gem 2.0.0, the "Powered by Shopify" link can be found in the section-footer.liquid in the Snippets folder of the theme. Look for the following code and delete it from the file:

{{ powered_by_link }}