Read this article : Clear the history and cookies from Safari on your iPhone, iPad, or iPod touch - Apple Support
and follow the steps in the article .
A cookie is a piece of data that a site puts on your device, so it can remember you when you visit again. Here's how to choose whether Safari blocks cookies:
- Tap Settings > Safari > Block Cookies.
- Choose an option: Always Block, Allow from Current Websites Only, Allow from Websites I Visit, or Always Allow.
If you block cookies, some web pages might not work. Here are some examples:
- You might not be able to sign in to a site using your correct username and password.
- You might see a message that cookies are required or that your browser's cookies are off.
- Some features on a site might not work.
Best settings is allow from websites I visit : Safari for Mac: Manage cookies and website data using Safari
If you choose always block :
Always block: Safari doesn’t let any websites, third parties, or advertisers store cookies and other data on your Mac. This may prevent some websites from working properly.
And , if allow from websites I visit is selected : Safari accepts cookies and website data only from websites you visit. Safari uses your existing cookies to determine whether you have visited a website before. Selecting this option helps prevent websites that have embedded content in other websites you browse from storing cookies and data on your Mac.