First, go to Settings in the browser.

You can find this by pressing the three dots at the top right -> "settings".

In this way, you go to "Privacy and Security" in the menu on the left.

Here you will find "Delete browsing data".

Press this and choose what you want to delete, and for what period of time.

Keep the following options unchecked and select the time period "All dates":

Select Safari -> Preferences.

Click on "Privacy".

Click on "Manage Site Data".

Select the website and click "Remove".