In order for you to change Base URL?
Step 1:
Login to CometChat Admin Panel.
Step 2:
From left side menu, click on "Settings->General"
Step 3:
search for "Base URL:"
Step 4:
Change "Base URL:" as per your requirement.
Step 5:
Click on "Update" button.
Step 6:
Click on "Clear Cache" from left side menu.
Step 7:
Clear Your Browser Cache.