Otherwise, you can access to the terminal addon into cockpit for manage the bash, allowing to use yum if you need it (without SSH if not needed).
Application page anyway should be the first step for removing modules of Nethserver.
I have the problem too. On all maschines and since Cockpit is the new UI.
If i klick “remove” under Applications/Package/three dots, there comes an Windows which aks: “are youre sure” with a text “Liste” (in german) and a spinning wheel (will not stop after hours). The Button “remove” is gray, only “cancel” is klickable.