While creating the campaign, the edit option is available in the ‘permission reminder’ section. Use the following HTML code to change/edit the text of the unsubscribe link/button:
Write content in the required language <a href="%%unsubscribe%%"> write content in the required language</a>
📌 Looking for the button on the unsubscribe page itself? The text of the Confirm Unsubscribe and Resubscribe buttons is changed in Account Settings › Unsubscribe Page. See Unsubscribe Page — Customization & Reason Analytics.