Persistent cookies web beacons and similar technologies placed in local storage

Delete the App Chrome/Firefox/Brave/Edge:

This is the only 100% effective method for non-Safari browsers on iPhone.

1. Long-press the browser app
2. Tap Delete App
3. Reinstall from the App Store

Deleting the app clears:

• Local Storage
• IndexedDB
• Cookies
• Service Workers
• Cache Storage
• Any persistent site data that the app was holding onto

Think of it as a hard reboot for the browser’s storage sandbox.

Clear Safari Website Data

1. Settings → Safari
2. Tap Advanced
3. Tap Website Data
4. Tap Remove All Website Data

This clears:

• Cookies
• Local Storage
• Session Storage
• IndexedDB
• WebSQL
• Service Workers
• AppCache

See the pic below

You may get better and prompt responses if you may kindly provide the iPhone Model that you have and the iOS version if it is known to you and re-post.

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...

Please re-post with detail so that someone else can help.

Regularly clearing your History and Website Data is a good habit for keeping your iPhone’s browsing activity private. Just note that iOS doesn’t offer an automatic way to do this — you have to run it manually.

See the pics below, which is self-explanatory