You can remove an object (Table, View, etc, …) from the Data Source by clicking the cross on the top right of the table :
If the table is in a relationship with other tables and removing it breaks Join conditions, a confirmation dialog appears :
All bindings related to this table will be lost. Do you want to proceed anyway ?
If you press OK, the Join Editor dialog appears and lets you fix the missing relationships (see below Chapter “Merging Data”).