What are some reasons you cannot remove a test process from a test plan?

According to the SAP S/4HANA Cloud, public edition Learning Journey1, some reasons you cannot remove a test process from a test plan are: the test process has not been made visible; data binding exists with another process. A test process is a unit of testing that represents a business process or scenario in SAP S/4HANA Cloud. A test plan is a collection of test processes that are executed in a specific order and scope. A test process can be made visible or invisible in a test plan depending on whether it is relevant for testing or not. Data binding is a feature that allows you to link data between different test processes in a test plan.