Downgrading WooCommerce version

Good day,

We took over a job with few bugs..

They are using a third party Gateway plugin that require WordPress 4.6 and not higher…

They are using version 2.6.14 (uodated been done) of WooCommerce and the plugin stopped.
Can we downgrade to version 2.6.5 ?? And how to do that without breaking everything ?

Can you guide me?

Thank you