the reference answer GPT ᴼ ᴾ ᴱ ᴺ ᴬ ᴵ
Based on the information you provided, I can preliminarily judge that the SMS you used is short for Surface-water Modeling System. In this case, you might consider using the grid editing tool in SMS to modify your grid.
First, you can use the "Select Grid Element" tool in SMS to select the area you want to delete. You can then use the Delete Grid Elements tool to remove these elements. If the line segment selection tool does not work, consider trying another tool, such as Box Select Grid Elements or Polygon Select Grid Elements.
After deleting the area, you need to use the "Edit Boundaries" tool in SMS to redefine land and water boundaries. You can optionally add new boundary points using the Insert Point tool and wire them together using the Insert Boundary Segment tool. If desired, you can also use the Move Point or Remove Point tools to fine-tune the boundaries.
Finally, save your changes and regenerate the model. Note that when performing this type of operation, it is important to back up the original data in case something unexpected happens.