If you need to deactivate your license you can do so in 2 ways.
Plugin Setting
Go to Contact > Klaviyo and click “Deactivate License”. Thats it!
Sitepact Account
There are times when deactivating your license key from the plugin setting screen may not be possible. In this case, you can do so from your Sitepact account.
Go to the order you made.
You can click the “Reset Usage” icon to deactivate your license.
If you have issues with this feel free to contact support by opening a ticket.