To solve this problem using a file manager (or FTP), rename your plugins folder. You can rename it anything – for example, “backupplugins”. This will disable all plugins. You’ll also need to clear your browser cache/history completely or use an incognito window so your browser doesn’t continue redirecting you.
Once you can log in successfully, you should be able to rename “backupplugins” back to just “plugins”. WordPress should still have them all deactivated. You can then activate them one by one through wp-admin. Log out and log back in each time to test and verify that the plugin you just activated isn’t messing up the login. Once you find the plugin that is causing issues, you can rename the plugins folder one more time, log in, rename plugins folder back to “plugins”, log in, reactivate all plugins except the problem one.