Can somebody explain how to remove the 90 km/h speed limit on Euro Truck Simulator 2?
You can remove the speed limiter from the gameplay settings by unticking "Truck Speed Limiter":
You need patch 1.4.1 or higher to use this setting.
Also note that external jobs provided by World of Trucks force the speed limiter on regardless of your preferences.
If you're using an earlier patch, there are mods that let you do this: