You can downgrade WordPress using a plugin or manually.

To downgrade WordPress by using a plugin:

1. From your WordPress admin, mouse over on ‘Plugins‘ and click on ‘Add New‘
2. Search for ‘Wp Downgrade‘
3. Download and activate the plugin
4. Mouse over on ‘Settings‘ and click on ‘WP Downgrade‘
5. In the WordPress Target Version field, enter the release you want to downgrade to
6. Click on ‘Save Changes‘ and, when prompted, click on ‘Update Core‘

You can reference the WordPress Releases archive to see all the WordPress versions.

Reference link for both plugin and manual: https://increasily.com/how-to-downgrade-wordpress/