Clear your browser caches. That might be an issue.
If problem still persists:
1. add plugin back
2. activate it
3. go to plugin settings, and set “Activate or Deactivate” to “Off”
4. then you can remove the plugin by deactivate and delete…
P.s. I have update version of this plugin that is compatible with WordPress 4.9.6, as there was issues with javascript. If anyone is interested in fixed version, please let me know.
