Safari (iOS)

1. Go to Settings → Safari
   (On iOS 18 and newer: Settings → Apps → Safari)  

1. Scroll down and tap Advanced → Website Data.

1. Find your domain (or use search), swipe left, and tap Delete.

1. Restart Safari and open the site again.
   To restart Safari: swipe up from the bottom (or double-press the Home button), find Safari in the app switcher, swipe it away to close it, then open it again from the home screen.

Alternative:  Go to Settings → Safari → Clear History and Website Data – to remove all data (cookies, history, etc.) at once.