Navigate to your repository page on GitHub.

Select Branches from the options on the left sidebar.

Click the icon to the right of the branch name to switch to another branch.

From the drop-down, select the branch that you want to switch to.

Next, click update to perform the switch.

Click the big red button saying that you understand the changes you're about to make. After that, your default branch is changed.

If you want to switch your repository's default branch, it is a straightforward process in GitHub. Follow these steps to get started.

How to Change Default Branch in GitHub