Go to the "My websites" section, which you can find at the top of your screen, as shown in the image below:

Choose the website you wish to delete, and click on the three-dot icon ("⋮") on the right-hand side.

Select "Remove".

If you enabled the Compact view, the "Remove" option can be found here:

Once you complete this step, the website will be deleted from your Wincher account.