Philo, I had opened another thread for this issue into WP hack category. And a member named BCWorkz replied. I am going to quote his post below. I followed his tips, and I was able to narrow down the problem to a plugin – (WPTouch Mobile Plugin ver 3.6) I had also downloaded WP fresh and replaced the WP-Admin\users.php file, before disabling all the plugins in my site, and then re-enabling them one at a time, testing the delete functionality each time. Here it is –
“Hmmm. That’s odd. Does the button exist in the page’s source code? It should be a half dozen lines above the footer output. If so, it is just hidden by CSS. You can use your browser’s inspector tool to identify where the applicable CSS rule is and correct it.
If it’s not there, confirm the PHP file responsible for it’s output is correct. wp-admin/users.php at line 258 should have a call to submit_button(). If not, download WP again and extract. You only need to upload the one file.
If it is there, some plugin has probably hooked ‘delete_user_form’ and failed to properly return. Deactivate all of your plugins, the button should reappear. If not change to a default theme. If it appears, reactivate each plugin one by one, testing for the button each time. When it disappears, the plugin you most recently activated is the culprit. Try deleting then reinstalling that one plugin. If that doesn’t help, seek support from the author.
If the button does not appear after deactivating all plugins and changing themes, there is a possibility your site has been compromised by hackers.”