I'm not sure I completely understand the steps you've taken ("spamming the uninstall button" means what??) but first do a simple Windows File Explorer search for "mb_DiscordBee.dll" to see if the file remains in some other folder. If so, delete it and restart MB. If it remains on the plugins list, try re-installing the plugin manually, then hitting the uninstall button again. If it's still on the list, and the plugin file is truly gone, there are other ways to remove the entry itself but first let's see what happens after the steps above.