If login misbehaves, clear data for this site. The login session cookie must be cleared on the server too (link below).
How to clear site data on your phone (browser settings)
- Chrome (Android): Tap ⋮ → Settings → Privacy and security → Clear browsing data. Choose a time range (or “All time”), enable Cookies and site data and Cached images and files, then Clear data. Alternatively: ⋮ → Info (ⓘ) on the address bar → Site settings → Clear & reset (wording varies by version).
- Chrome (iPhone/iPad): Open Chrome → ⋯ → Settings → Privacy and Security → Clear Browsing Data → choose what to clear → confirm.
- Safari (iPhone/iPad): For everything: Settings → Safari → Clear History and Website Data. For one site: Settings → Safari → Advanced → Website Data → find the site → swipe left to delete.
- Samsung Internet: ☰ → Settings → Personal browsing data → Delete browsing data → select cookies/cache → delete.
JavaScript cannot remove some cookies (e.g. HttpOnly session cookies); use “Clear server session cookie” above or the browser’s own controls.