This document explains how to clear Safari's saved passwords and form data on iOS.Note: These screenshots were taken from various iOS devices, the general procedure should apply.
Locate and tap the Settings App.
Scroll down and tap the Accounts & Passwords option.
Tap App & Website Passwords. You may be asked to enter a passcode, or authenticate with TouchID or FaceID.
You may delete between one or all passwords.
To Delete A Single Password:
Swipe left on the item you wish to delete, and press the red Delete area when it appears.
To Delete Multiple Or All Passwords:
Tap Edit in the top right corner, then select all of the items you would like to remove, then tap Delete.