If you still have access for the site
Just click on the Deactivate button in the Product Activation box and you are all set. The purchase code that you've used for that site will be available to activate other installations.
If you no longer have access for the site
We've made an online utility where you can list all your purchases and the sites where you've activated LayerSlider. From there, you will be able to remotely deactivate any site you wish. Please visit: https://account.kreaturamedia.com/
If you no longer have access to your account or someone else purchased LayerSlider on your behalf
In cases like these, please open a support ticket or contact us via our Contact Form and ask for help in order to restore your account or transfer licenses to another account. Please also provide any proof you can in order to confirm your identity as we handle data security and personal information very seriously.