Deletion failed: There has been a critical error on this website.

I have a few issues, all centering around the same issue. I have Nitropack installed, and a plugin called “Speed Optimizer” is causing it to not load my site correctly. The tech support at Nitropack notified me of this. The issue I have though, is I had a critical error message this morning. So, what happens is, every time I try to delete that plugin, I get the “Deletion failed: There has been a critical error on this website.” message.

I have tried deactivating all the plugins, but I still get that same error message when trying to delete the plugin. I have even installed a backup of a couple of days ago, but I still get the same thing.

All my plugins are up to date. I have no idea how to solve this.