To delete design strips, two methods are available, including:

In the model explorer window on the left, right-click the design strip to be deleted, then select Delete. To delete multiple strips, hold Crtl while selecting the strips to be deleted, then right-click any one of these strips and select Delete These Objects.
Open the interactive database editing table by selecting Model Definition > Geometric Data > Design Strip Object Geometry > Table Object Geometry - Design Strips. Highlight the records of design strips to be deleted, then select Delete Record > Apply to Model.

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