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Hi i downloaded essential plugin for my personal Aternos server but i uninstalled it becase only operators can place block and interact with the world , now in my server there are no installed plugins but essentials still remain how can i remove it? 
edit: i don't know now which essential plugin still in my game but, is there a command to unlock interaction with the world for other players? so is the easyer way to fix it,
please remove essentials[antibuild what so ever].jar file
You can manage your plugins at the Files & Plugins page. Make sure to uninstall plugins while your server is offline. Click on the little trash icon next to a plugin's name and confirm the deletion to delete it.
Then you don't have any plugins anymore already, that's what you wanted, right? Mind that you can only build outside the spawn protection.
I just checked your server, you've got Vanilla Minecraft, so it's impossible Essentials is loaded. If you can't build mind that it's because of the spawn protection, not because of the plugin.
It's not possible to remove the spawn-protection for now.
OPs should be able to bypass the spawn protection.
